Cradle and cable handler for a test head manipulator

ABSTRACT

In one aspect, a cradle system for supporting a load, the cradle system comprising a first arm with a first carriage assembly axially adjustable therealong and a second arm, opposite the first arm, with a second carriage assembly axially adjustable therealong. An actuator is associated with the first and second carriage assemblies and configured such that actuation of the actuator causes the first and second carriage assemblies to move axially in opposite directions. In another aspect, a cable support system comprising a support column and one or more tethers supported by the support column and configurable so that at least one tether is configured to move its supported cable in the same or opposite direction as the test head moves at a rate that is a constant multiplied by the test heads rate of motion where the constant may be greater than, equal to, or less than one.

THIS APPLICATION IS A U.S. NATIONAL PHASE APPLICATION OF PCT INTERNATIONAL APPLICATION PCT/US2008/005906.

BACKGROUND OF THE INVENTION

The present invention relates to a testing device, and more particularly, to a cradle and cable handler for a test head manipulator.

U.S. Pat. No. 5,931,048 to Slocum, which is included for all of its teachings by reference, describes a test head positioner or manipulator that includes a cradle (FIG. 6 of '048) for holding a test head. Mechanisms within this cradle allow the test head to be moved in directions (defined in FIG. 2 of '048) In-Out, Nod Up-Down, and Theta Left-Right. (Nod motion may also be referred to as pitch or tumble elsewhere in the literature and herein. Theta motion may sometimes be referred to as yaw motion elsewhere in the literature and herein.) Each of the two sides of the test head is coupled to one of two cradle arms. A motorized actuator is provided in each of the two cradle arms to move that arm's test head coupling linearly along the arm. If the two actuators move their respective coupling in the same direction, In-Out motion is achieved. If the two actuators move their respective couplings in opposite directions, Theta Left-Right motions are achieved. The motor driven actuators include clutch mechanisms. With the clutches disengaged, a relatively small external force may be applied to move the test head slightly with respect to the cradle. This provides compliance to enable a test head dock to finely position the test head with respect to a test peripheral such as a package handler or wafer prober. This is a relatively complex and expensive solution in that it requires electromagnetic components and a controller to coordinate the motions of the two actuators. The '048 patent also identifies that the handling of the cable that connects the test head to a mainframe is difficult and complicates smooth positioning of the test head. As cables become increasingly large and awkward due to the inclusion of more conductors, air ducts for cooling, and hoses and tubing for conveying liquid coolants, this problem has grown increasingly difficult.

SUMMARY OF THE INVENTION

In an exemplary embodiment, a cradle includes theta motion by using a single actuator, which may be a manual crank or handle, or it may be motorized.

In one aspect of the invention, a cradle system for supporting a load is provided. The cradle system comprises a first arm with a first carriage assembly axially adjustable therealong and a second arm, opposite the first arm, with a second carriage assembly axially adjustable therealong. An actuator is associated with the first and second carriage assemblies and configured such that actuation of the actuator causes the first and second carriage assemblies to move axially in opposite directions.

In a further exemplary embodiment, integrated driven theta/tumble motion is provided within a cradle including compliance in theta, tumble and in-out degrees of freedom.

A further exemplary embodiment provides a scheme of cable handling. In one aspect of the invention, the cable support system comprises a support column and one or more tethers supported by the support column and configurable so that at least one tether is configured to move its supported cable in the same or opposite direction as the test head moves at a rate that is a constant multiplied by the test heads rate of motion where the constant may be greater than, equal to, or less than one.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIGS. 1A and 1B are three-dimensional views of the overall test system.

FIGS. 2A and 2B are three-dimensional views of a test head cradle that incorporates an exemplary embodiment of the invention, including a coordinate system that is attached to the cradle.

FIGS. 3A and 3B are three-dimensional views of mechanisms contained within the cradle with the cradle sides and other cradle structures hidden.

FIG. 4A is a partially exploded isometric view of the cradle.

FIG. 4B is a more detailed view of certain components in FIG. 4A.

FIG. 4C is an exploded three-dimensional view of certain components which are hidden in FIG. 4A.

FIG. 5 is a exploded three-dimensional view of a theta drive unit and associated apparatus that includes a tumble gearbox.

FIG. 6 is a three-dimensional view of the theta drive actuator combined with the tumble drive actuator.

FIG. 7 is a three-dimensional view of the mechanisms shown in FIG. 6 mounted in one arm of the cradle.

FIGS. 8A and 8B are two three-dimensional views of a theta/tumble mounting assembly including tumble motion stops.

FIGS. 8C and 8D are two exploded views of the assembly shown in FIGS. 8A and 8B.

FIG. 8E is a front view of a portion of the assembly shown in FIGS. 8A and 8B.

FIGS. 9A and 9B are two three-dimensional views of a theta/tumble mounting assembly including a tumble drive gear box.

FIGS. 9C and 9D are two exploded views of the assembly shown in FIGS. 9A and 9B.

FIG. 10A is a three-dimensional view of the apparatus of FIGS. 8A and 8B coupled to the interior of a cradle arm.

FIG. 10B, derived from FIG. 10A, shows theta carriages slidingly attached to a mounting block.

FIG. 10C is a partially exploded view of FIG. 10B.

FIG. 11A is a three-dimensional view of a tumble drive gear box.

FIG. 11B is a partially exploded view of the apparatus in FIG. 11A.

FIG. 12A is a side view of the apparatus shown in FIG. 11A defining a sectional view provided in FIG. 12B.

FIG. 12B is the sectional view defined in FIG. 12A.

FIG. 13A is a three-dimensional view of the interior of a cradle arm where the tumble drive apparatus is located.

FIG. 13B is a partially exploded view of FIG. 13A.

FIG. 14A is a three-dimensional view of a theta carriage extension assembly that includes tumble drive apparatus and that is included in the view shown in FIGS. 13A and 13B.

FIG. 14B is an alternate view of the equipment shown in FIG. 14A.

FIG. 15A is a three-dimensional view of the interior of the cradle arm shown in FIGS. 13A and 13B with the equipment of FIG. 14A removed.

FIG. 15B is a close up taken from FIG. 15A to illustrate a theta limit apparatus.

FIG. 15C is a three-dimensional view of a theta limit block.

FIG. 16 is an alternate cradle having a single theta drive handle.

FIGS. 17A and 17B are three-dimensional views of a test head cradle that incorporates an alternative exemplary embodiment of the invention.

FIG. 17C is a more detailed view of a portion of one of the cradle arms of the test head cradle of FIGS. 17A and 17B.

FIG. 17D is a three-dimensional view showing the connection between the theta drive handle and carriage assembly of the embodiment of FIGS. 17A and 17B with the cradle structure removed from view for clarity.

FIG. 18A is a three-dimensional view of a carriage assembly of the embodiment of FIGS. 17A and 17B.

FIG. 18B is a exploded three-dimensional view of the carriage assembly of FIG. 18A.

FIG. 18C is an end elevation view of the carriage assembly of FIG. 18A.

FIG. 19A is a three-dimensional view of another carriage assembly of the embodiment of FIGS. 17A and 17B.

FIGS. 19B-19D are exploded three-dimensional views of the carriage assembly of FIG. 19A shown from different perspectives and different levels of explosion.

FIG. 19E is a plan view of the carriage assembly of FIG. 19A.

FIG. 19F is an end elevation view of the carriage assembly of FIG. 19A.

FIG. 19G is an exploded three-dimensional view of a side support assembly of the carriage assembly of FIG. 19A.

FIG. 19H provides three-dimensional views of a threaded compression insert of the carriage assembly of FIG. 19A.

FIG. 19I is a cross sectional view of a control and compliance apparatus of the carriage assembly of FIG. 19A.

FIG. 193 provides three-dimensional views of stepped tumble shafts of the carriage assemblies of FIGS. 18A and 19A.

FIGS. 20A and 20B are three-dimensional views of a test head cradle that incorporates an alternative exemplary embodiment of the invention.

FIG. 20C is a more detailed view of a portion of one of the cradle arms of the test head cradle of FIGS. 20A and 20B.

FIG. 21A is a cross sectional view along the line 21A-21A in FIG. 20B.

FIG. 21B shows the cross section of FIG. 21A in perspective.

FIG. 22 is a three-dimensional view showing the connection between the theta drive handle and carriage assembly of the embodiment of FIGS. 20A and 20B with the cradle structure removed from view for clarity.

FIG. 22A is a more detailed view of a portion of FIG. 22.

FIG. 23 is a three-dimensional view of a traveler block of the carriage assembly of FIG. 22.

FIG. 24 is a three-dimensional view of a cylindrical nut of the carriage assembly of FIG. 22.

FIGS. 25 and 25A correspond to FIGS. 22 and 22A, respectively, but with portions of the traveler block cut away.

FIG. 26 is a perspective view of a test system that includes cables coupling a test head to a cabinet.

FIG. 27 is a schematic view of an exemplary embodiment of a cable support apparatus for a test system such as the one shown in FIG. 26.

FIG. 28 is a schematic view of an alternative exemplary embodiment of a cable support system.

FIGS. 29A through 29D are four schematic views of alternative cable support mechanisms, each having different support characteristics.

FIG. 30 is a perspective view of an alternative test system that includes cables coupling a test head to a cabinet.

FIG. 31 is a rear perspective view of the test head system of FIG. 30.

FIG. 32 is a schematic view of an exemplary embodiment of a cable support apparatus for a test system such as the one shown in FIG. 30.

FIGS. 33A through 33E are schematic views of alternative cable support mechanisms, each having different support characteristics.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A and 1B show test head positioner (or manipulator) 100 in accordance with an exemplary embodiment of the present invention. Positioner 100 includes base 115 and column 130. Column 130 allows test head 110 to be moved up and down for a vertical movement. Arm unit 140 moves up and down along column 130 through exemplary mechanisms, which are described below. Arm unit 140 may provide for motion in various degrees of freedom, which is also described below. Coupled to arm unit 140 is cradle 200, having two arms 290 a and 290 b. Test head 110 is able to be moved with various degrees of freedom within cradle 200. The various degrees of freedom that are permitted within cradle 200 are now described.

Test head manipulator 100 is described in more detail in co-pending PCT International Patent Application No. PCT/US2008/002134 which is incorporated herein by reference.

FIGS. 2A and 2B provide two perspective views of cradle 200. Cradle arms 290 a and 290 b include mechanisms that enable an operator to rotate handles 270 a,b and 280 a,b to cause a test head to move relative to the cradle in two degrees of freedom, which will be referred to as “operator-controlled” or “operator-driven” motions. The mechanisms also allow compliant motion (or compliance) of the test head relative to the cradle in three degrees of freedom. Compliance may be defined as placing an object in a condition (sometimes referred to as “substantially weightless”) where it may be moved with a relatively small external force. FIGS. 2A and 2B include coordinate system 10, which may be considered to be attached to cradle 200 such that the XZ plane is parallel to a plane defined by cradle arms 290 a and 290 b. Rotation about the X axis may be referred to as tumble motion (theta X) and is equivalent to the Nod motion in the '048 patent. Also rotation about the Y axis may be referred to as yaw or “theta” motion (theta Y) and is equivalent to the Theta motion defined in the '048 patent. Finally, the Z-axis of coordinate system 10 is parallel to cradle arms 290A and 290B and corresponds to the In-Out axis of '048.

Exemplary operator-driven motions which may be provided to test head 110 within cradle 200 may include tumble motion (theta x), and yaw or “theta” motion (theta y). Compliant motion or compliance is provided within the cradle and includes Tumble (theta X), yaw (theta Y), and In-Out (linear Z).

We now provide an overview of the major components included in cradle 200 and their interactions. Although operator-driven motions are described as being accomplished by means of an operator rotating a handle, it will be apparent to those of ordinary skill that electromechanical, pneumatic or other types of actuators could be substituted along with appropriate controllers.

Referring to FIGS. 2A and 2B, side supports 740 a and 740 b are provided and coupled by carriage assemblies 751 a and 751 b to cradle arms 290 a and 290 b respectively. As seen in FIGS. 1A and 1B, test head 110 may be attached to side supports 740 a and 740 b using appropriate fasteners such as screws. Side supports 740 a and 740 b are mounted to carriage assemblies 751 a and 751 b so that each can pivot approximately plus or minus five degrees (or less) about respective axes 202 a and 202 b that are parallel to cradle 200's Y axis and that pass approximately through its respective cradle arm 290 a or 290 b. Also side supports 740 a and 740 b are designed so that they rotate at least approximately 90 degrees about a common tumble axis 201 in a plane parallel to the XZ plane and which is within plus or minus five degrees (or less) of being parallel to the X axis. Preferably, test head 100 is attached so that a line extending along the common rotation axis (axis 201) of side supports 740 a and 740 b passes approximately through its center of gravity.

Carriage assembly 751 b includes gear box 750, which is coupled to tumble drive handles 280 a and 280 b by means of timing belt 1980 and other apparatus to be described later. Drive handles 280 a and 280 b are directly coupled to one another by means of a common shaft. Rotation of either handle 280 a or 280 b causes rotation of the shaft and the other handle. Rotation of either handle 280 a or 280 b is transmitted to gear box 750, causing side support 740 b to rotate about the previously described tumble axis 201. As side support 740 b is fixed to test head 110, test head 110 correspondingly rotates about tumble axis 201. Carriage assembly 751 a does not include a gear unit. Rather, side support 740 a is coupled with bearings to carriage assembly 751 a in a manner that allows it to freely rotate about axis 201. Thus, as test head 110 rotates about axis 201, side support 740 a freely rotates with it. Gear box 750 includes means to be described later that allows test head 110 to be rotated slightly about axis 201 in response to a relatively small external force, thus providing compliance in tumble rotation. Carriage assembly 751 a includes stops to limit tumble motion to a predefined range such as approximately 90 degrees.

Carriage assemblies 751 a and 751 b are rigidly coupled to carriage extensions 730 a and 730 b respectively. Carriage assemblies 751 a and 751 b are slidingly mounted on the insides of cradle arms 290 a and 290 b respectively, such that carriage assemblies 751 a and 751 b may be moved linearly, back-and-forth, in the “In-Out” or Z-axis direction. It is to be understood that carriage extensions 730 a and 730 b move with their respective carriage assemblies 751 a and 751 b. Shafts 250 a and 250 b are coupled to theta driving handles 270 a and 270 b respectively to allow an operator to move carriage assemblies 751 a and 751 b back and forth. Clockwise rotation (viewed from handle 270 a) of shaft 250 a causes carriage assembly 751 a to slide in the “Out” direction, and counterclockwise rotation of shaft 250 a causes carriage assembly 751 a to move in the “In” direction. Similarly, clockwise rotation (viewed from handle 270 b) of shaft 250 b causes carriage assembly 751 b to slide in the “Out” direction, and counterclockwise rotation of shaft 250 b causes carriage assembly 751 b to move in the “In” direction. Shafts 250 a and 250 b are coupled to one another by means of belt 222 so that rotation of one of shafts 250 a and 250 b causes rotation of the other of shafts 250 a and 250 b. Because belt 222 forms a figure eight, shafts 250 a and 250 b rotate in opposite directions. Thus, rotation of either handle 270 a or 270 b will cause one of carriage assemblies 751 a and 751 b to move “In” while the other moves “Out.” Thus, axis 201 may be rotated in a plane parallel to the XZ plane imparting Theta or yaw motion to test head 110. Because side supports 740 a and 740 b are allowed to pivot about axes 202 a and 202 b respectively, this motion is not inhibited. The connection between shafts 250 a and 250 b and their respective carriage assemblies 751 a and 751 b incorporates mechanisms (to be described later) that allow carriage assemblies 751 a and 751 b to move compliantly with respect to shafts 250 a and 250 b respectively. This enables test head 110 to be moved compliantly in both the “Theta” (yaw) and “In-Out” degrees of freedom.

Now, having provided a brief overview, we turn to a more detailed description of an exemplary embodiment.

Referring to FIGS. 3A and 3B and FIGS. 4A and 4B, yaw is permitted through various components which are coupled, for example, to cradle 200. In FIG. 4A, cradle 200 is shown. In FIGS. 3A and 3B, the exterior structure of cradle 200 has been hidden. Yaw motion is accomplished through the rotation of shaft 250 a and/or shaft 250 b. As shown in FIGS. 3A and 3B, shafts 250 a and 250 b are coupled together so that rotation of one causes rotation of the other, and vice-versa. Furthermore, in order to cause yaw motion of test head 110, it is desirable for the rotation of one of shafts 250 a, 250 b in one direction to result in the rotation of the other of shafts 250 a, 250 b in an opposite direction. Put another way, if shaft 250 a is rotated in a first direction, then it is desirable for the rotation of shaft 250 a to result in the rotation of shaft 250 b in a second direction opposite to the first direction. Similarly, if shaft 250 b is rotated in a first direction, it is desirable for the rotation of shaft 250 b to result in the rotation of shaft 250 a in a direction opposite to the first direction.

This ability for the rotation of one of the shafts to result in rotation of the other of the shafts in an opposite direction is accomplished using a coupling assembly, for example, belt 222. As shown in FIG. 4A, belt 222 loops around pulley 610 a and pulley 610 b. Also, as shown, belt 222 “crisscrosses” itself as it travels between pulley 610 a and pulley 610 b, forming a FIG. 8. As further shown in FIGS. 3A and 3B, cable 222 is maintained in a path along the interior of cradle 200 through the use of pulleys 221 b, 221 c, 501 b, 501 c, 501 f, 501 g, 221 f, and 221 g. Belt 222 is made of a rubberized material and is round in cross section. Thus, there is ample friction to enable one shaft to readily drive the other shaft. Further, the belt is purchased as a standard length item, and it may be slightly stretched when it is installed. Its path within cradle 200 is designed so that it may be slipped or “snapped” into place without any tensioning adjustments necessary.

Pulleys 221 b, 221 c, 501 b, 501 c, 501 f, 501 g, 221 f, and 221 g are idler pulleys that freely rotate as the belt moves along its path. Pulleys 501 b, 501 c, 501 f, and 501 g simply rotate on shafts that are attached to internal surfaces of cradle 200 through structures, which would be understood to one of ordinary skill in the art. Pulleys 221 b, 221 c, 221 f, and 221 g are held in position above and below respective pulley mounts, also understandable to one of ordinary skill in the art.

Theta driving handles 270 a and 270 b may be coupled to shafts 250 a, 250 b respectively with appropriate means, such as keys, in order to facilitate rotation of shafts 250 a and 250 b. As shown, for example, in FIGS. 4B and 4C, shaft 250 a extends through an opening in pulley 610 a which includes key slot 611 a. Key 615 a is inserted in opening 614 a in shaft 250 a. Key 615 a engages the key slot 611 a of pulley 610 a. Shaft 250 a includes shoulder 618 a against which pulley 610 a is placed. Thus, as pulley 610 a is installed onto shaft 250 a, pulley 610 a will not move past shoulder 618 a. Furthermore, because key 615 a is included, rotation of shaft 250 a causes rotation of pulley 610 a. Furthermore, pulley 610 b includes a key slot arrangement similar to that of pulley 610 a, and shaft 250 b includes a shoulder and a key similar to shoulder 618 a and key 615 a included in shaft 250 a. Thus, rotation of shaft 250 b results in rotation of pulley 610 b. Furthermore, as explained above, by virtue of belt 222, rotation of pulley 610 a causes rotation of pulley 610 b. Similarly, rotation of pulley 610 b causes rotation of pulley 610 a.

Because belt 222 crisscrosses itself as shown, as pulley 610 a rotates in one direction, pulley 610 b rotates in a direction opposite to that of pulley 610 a and vice-versa.

As seen in FIG. 4A, shaft 250 a extends through opening 690 a in cradle 200. Similarly, shaft 250 b extends through opening 690 b in cradle 200.

Referring also to FIG. 3B, shaft 250 a extends through an opening in pillow block 630 a. Pillow block 630 a is attached to an inner wall of side 290 a of (not shown in FIG. 3A) cradle 200. Idler pulleys 221 b and 221 c are mounted to pulley mount 631 a, which is in turn attached to pillow block 630 a. Appropriate bearings may be situated between pulley 610 a and pillow block 630 a. Shaft 250 a thus extends through pillow block 630 a until it reaches shaft coupling 255 a. Shaft 250 a is thus inserted into one end of shaft coupling 255 a. Threaded member 260 a is inserted into the other end of shaft coupling 255 a. Shaft coupling 255 a clamps down on the respective ends of threaded member 260 a and shaft 250 a inserted therein so that threaded member 260 a rotates as shaft 250 a is rotated. Threaded member 260 a is threaded into cylindrically-shaped nut 702A that is rigidly attached to cylindrically-shaped nut extension 704 a.

We next refer to FIG. 4C to describe the relationship between shaft 250 a and pillow block 630 a. The situation is the same for shaft 250 b and its pillow block 630 b; thus, the information need not be repeated. As previously described, pulley 610 a is keyed to shaft 250 a and abuts shaft shoulder 618 a. Pulley 610 a may not be moved beyond shoulder 618 a. Ball bearings 621 a and 622 a are fitted into circular opening 625 a in pillow block 630 a. Shaft 250 a may be received by ball bearings 621 a and 622 a so that, when assembled, shaft portion 626 a is located and may freely rotate within pillow block 630 a. Thrust bearings 628 a may be fitted on shaft 250 a and located between pillow block 630 a and pulley 610 a. Retaining ring 631 a is fitted into circumferential slot 633 a in shaft 250 a. Pulley 610 a and thrust bearings 628 a prevent shaft 250 a from moving in the “Out” direction; retaining clip 631 a prevents motion of shaft 250 b in the “In” direction. Thus, when assembled, shaft 250 a may freely rotate within pillow block 630 a but is constrained so that it cannot move in the “In-Out” direction, which is parallel to the Z axis.

We next refer to FIGS. 5, 6, and 7 which show in more detail the structure within arm 290 b of cradle 200. Carriage extension 730 b is removed from FIG. 2B to create FIG. 7. Arm structure 290 b and various other apparatus have been removed from FIG. 7 to create FIG. 6. FIG. 5 is an exploded view of a subassembly comprising theta carriage extension 730 b, theta carriage assembly 751 b, and their coupling to threaded member 260 b. The view in FIG. 5 is from inside cradle side 290 b looking towards the inside of carriage extension 730 b.

Referring to FIGS. 5, 6 and 7 and recalling FIGS. 2A and 3A, shaft 250 b extends through opening 690 in arm 290B of cradle 200. Shaft 250 b then extends through an opening in pillow block 630 b (which is also fixed to the inner wall of arm 290 b of cradle 200). The assembly including shaft 250 b, pillow block 630 b, and pulley 610 b is the same as previously described with respect to shaft 250 a. Thrust bearings, ball bearings and a retaining clip are all used as previously described. Shaft 250 b is inserted into an end of a shaft coupling 255 b. Threaded member 260 b extends from the opposite end of shaft coupling 255 b.

Threaded member 260 b extends into the threaded opening of cylindrical nut 702 b. Threaded member 260 b is shown to the right of nut 702 b in FIG. 5. Nut 702 b may move linearly along threaded member 260 b as threaded member 260 b is rotated with respect to nut 702 b. Nut 702 b is rigidly coupled to shaft 704 b by means of screws 1704. In this manner, as nut 702 b moves linearly, shaft 704 b moves with nut 702 b. The nut 702 b and shaft 704 b define a portion of the conversion assembly that converts the rotative motion into axial, linear motion. This specific conversion assembly is described here, while similar conversion assemblies are described with respect to the other embodiments.

Threaded member 260 b extends within shaft 704 b. Thus, threaded member 260 b moves in and out within shaft 704 b. In effect, the combination of nut 702 b and shaft 704 b comprises an extended nut. Shaft 704 b includes extension member 706 b rigidly mounted thereto. In an exemplary embodiment, extension member 706 b and shaft 704 b may be machined from a single piece of metal. The terminal end of extension member 706 b may include threaded end portion 708 b. Extension member 706 b and threaded extension end 708 b extends through spring 710 b, an opening in L-bracket 712 b, and spring 714 b. Threaded extension 708 b is then threaded through anti-rotation block 716 b such that a portion extends beyond anti-rotation block 716 b. Flat washer 718 b is passed over the end of threaded extension 708 b. Hex nut 720 b is then threaded onto threaded extension 708 b and tightened against flat washer 718 b and anti-rotation block 716 b. Anti-rotation block 716 b is not attached to carriage extension 730 b. Rather, it is sized and shaped such that it may readily slide along the inside of carriage extension 730 b without rotating. Thus, carriage extension 730 b may move linearly with respect to shaft 704 b and extension member 706 b while shaft 704 b and extension member 706 b are prevented from rotating as shaft 250 b is rotated.

L-bracket 712 b is rigidly mounted to carriage extension 730 b. Thus, as shaft 704 b moves, carriage extension 730 b moves with it. Furthermore, the springs 710 b and 714 b define a biasing assembly that functions to provide compliance to carriage extension 730 b. Compliance may be defined as placing an object in a condition where it may be moved with a relatively small external force. In this particular situation, the compliance afforded by springs 710 b, 714 b allows carriage extension 730 b to have a small amount of “wiggle” room. Thus, carriage extension 730 b (and anything coupled to carriage extension 730 b) can easily be moved small distances without rotating shafts 250 a, 250 b. As will be explained later, test head 110 is coupled to and moves with carriage extension 730 b. Thus, because of the compliance afforded by springs 710 b, 714 b, it is possible to move test head 110 small distances by simply pushing or pulling on test head 110. This feature is particularly desirable when docking a test head with a test peripheral such as a prober or package handler. Sometimes, after rotating shaft 250 b, test head 110 maybe slightly misaligned with a test peripheral to which it is to be desirably docked. The compliance feature afforded by springs 710 b, 714 b allows the docking mechanism or the operator to move test head 110 to address slight misalignment between test head 110 and the test peripheral.

To briefly summarize, rotation of theta drive handle 270 b causes rotation of shaft 250 b and threaded member 260 b. Shaft 250 b is mounted in pillow block 630 b so that it can freely rotate, but not move linearly. Nut 702 b is coupled through shaft 704 b to anti-rotation block 716 b and thus prevented from rotating. Threaded member 260 b is threaded into nut 702 b and extends into an opening in shaft 704 b. Thus, as handle 270 b is rotated, nut 702 b moves linearly along threaded member 260 b. Angle bracket 712 b is rigidly attached to carriage extension 730 b. Shaft extension 706 b couples shaft 704 b to angle bracket 712 b by means of springs 710 b and 714 b. Thus, as nut 702 b and shaft 704 b move linearly, carriage extension 730 b is urged to move linearly with them. However, when nut 702 b is maintained in a fixed position, an external force, sufficient to overcome the forces of springs 710 b and 714 b, may also move extension carriage 730 b linearly, providing compliance.

Referring again to FIG. 3B, it is seen that theta drive handle 270 a is coupled to carriage extension 730 a in an identical manner as just detailed for the coupling of theta drive handle 270 b to carriage extension 730 b. Thus rotation of handle 270 a causes linear motion of carriage extension 730 a. Further, as shaft 704 a and shaft extension 706 a are coupled to carriage extension 730 a by way of springs 710 a and 714 a, linear compliance is also provided for carriage extension 730 a.

In an exemplary embodiment, both threaded members 260 a and 260 b have right hand threads. Recall that belt 222 is arranged so that rotating one of threaded members 260 a and 260 b in a first direction causes the other to rotate in the opposite direction. Thus, rotating either theta drive handle 270 a or 270 b will cause carriage extensions 730 a and 730 b to move linearly in opposite directions. In particular, if we take the “Out” direction to be towards the closed end of cradle 200 and the “In” direction to be towards the open end, then rotation of theta drive handle 270 b in a clockwise direction (when viewed from the open end of cradle 200) causes carriage extension 730 b to move in the “In” direction and carriage extension 730 a to move in the “Out” direction. In practice, only one of the two theta drive handles 270 a and 270 b is required. One or the other or both may be installed as best suits the particular application. (Note, however, that if one of threaded members 260 a and 260 b is right hand threaded and the other of threaded members 260 a and 260 b is left hand threaded, then the same effect will be achieved when belt 222 does not form a figure eight and both shafts rotate in the same direction.)

Thus, as described above, carriage extensions 730 a and 730 b are capable of “In-Out” sliding motion. Carriage extensions 730 a and 730 b are coupled to theta carriage assemblies 751 a and 751 b respectively. Theta carriage assembly 751 b is combined with components associated with the tumble drive whereas carriage assembly 751 a is simpler. Referring to FIG. 5, theta carriage assembly 751 b, which includes first theta carriage 752 b, second theta carriage 754 b, first mid plate 756 b and second mid plate 758 b, is described. More specifically, as shown in FIG. 5, the upper right corner of first theta carriage 752 b is coupled to the upper left corner of first mid plate 756 b. The upper left corner of second theta carriage 754 b is coupled to the upper right corner of first mid plate 756 b. The lower right hand corner of first theta carriage 752 b is coupled to the lower left corner of second mid plate 758 b. The lower left corner of second theta carriage 754 b is coupled to the lower right corner of second mid plate 758 b.

Theta carriage 754 b is attached to theta carriage extension 730 b, thus attaching theta carriage assembly 751 b to carriage extension 730 b. Thus, theta carriage assembly 751 b moves with carriage extension 730 b.

As further shown in FIG. 5, linear bearing assemblies 760 are also included. Linear bearing assemblies 760 are attached to respective top and bottom locations of theta carriages 752 and 754. As shown in FIG. 5, the two upper bearing assemblies 760 include bearings 762 facing upwards. Furthermore, the two lower bearing assemblies 760 include bearings 762 facing downwards.

Bearings 762 engage linear rails 770 b, which are attached to base plate 780 b (FIGS. 7, 2B and 3B for example), which is in turn attached to the inner wall of arm 290 b of cradle 200. Further details regarding the interface between bearings 762 and those rails are described below.

Also shown in FIG. 5 is gear box 750 attached to tumble/theta block 755 b. Tumble/theta block 755 includes pivot journals 802 b, 804 b. Pivot journals 802 b, 804 b are inserted into opening 766 b of first mid plate 756 b and opening 768 b of second mid plate 758 b, respectively. Pivot journals 802 b, 804 b are inserted into openings 766 b and 768 b respectively before theta carriages 752 b and 754 b are attached to mid plates 756 b and 758 b. Openings 766 b and 768 b are equipped with flange bearings 801 b and 803 b respectively, so that tumble/theta block 755 b may freely pivot within theta carriage 751 b.

We now turn to more detailed, individual descriptions of theta carriages 751 a and 751 b because, although similar, each has unique characteristics. We begin with theta carriage 751 a, which is the simpler of the two.

FIGS. 8A through 8E are provided to describe theta carriage 751 a. FIGS. 8A and 8B provide two perspective views of theta carriage 751 a assembled to first and second mid plates 756 a and 758 a. Also included is side support 740 a, which is coupled to test head 110 (not shown). In a similar manner as discussed above, first and second mid plates 756 a and 758 a may be attached to theta carriages 752 a and 754 a (not shown in this series of Figures).

FIGS. 8C and 8D provide two exploded views of the apparatus shown in FIGS. 8A and 8B. Tumble/theta block 755 a is attached to spacer 820 a with appropriate fasteners. Two socket head cap screws 821 a and 822 a protrude from spacer 820 a to act as stops as is subsequently explained. Opening 1756 a extends centrally through tumble/theta block 755 a and spacer 820 a.

Tumble/theta block 755 a includes coaxial pivot journals 802 a and 804 a. Mid plates 756 a and 758 a include openings 766 a and 768 a respectively. Flange bearings 801 a and 803 a are fitted into openings 766 a and 768 a respectively. Pivot journals 802 a and 804 a may then be fitted into flange bearings 801 a and 803 a respectively to enable tumble/theta block 755 a to smoothly pivot about an axis defined by coaxial pivot journals 802 a and 804 a.

Stepped shaft 825 a, which includes key way 826 a is fitted to opening 1756 a in the following manner. Bearings 851 a (as well as other appropriate bearings which are not visible) are first fitted into opening 1756 a. Stop unit 840 a is keyed with key 827 a, for example, to shaft 825 a and is butted against shoulder 828 a. The small diameter section 829 a of shaft 825 a may then be inserted into opening 1756 a and advanced until rear section 841 a of stop unit 840 a rides against bearing inside opening 1756 a. In its proper position, rear section 841 a is close to, but does not contact, the surface of spacer 820 a. Shaft sleeve 853 a may be inserted into opening 1756 a from the opposite side. Sleeve 853 a is also keyed to shaft 825 a and is located between the surface of shaft 825 a and bearings 851 a (and others not visible). Shims and washers 854 a, retainer 856 a, and screw 855 a then complete the assembly in a manner that one of ordinary skill in the art will understand. Thus, shaft 825 a may freely rotate about its axis, which is perpendicular to the axis defined by pivot journals 802 a and 804 a. The rotational axis of shaft 825 a defines one end of tumble axis 201, and the axis defined by pivot journals 802 a and 804 a will define axis 202 a. (FIGS. 2A and 2B).

Side support 740 a is rigidly attached to shaft 825 a in a manner that allows the position of side support 740 a to be adjusted within plus or minus a few millimeters along the axis of shaft 825 a. Expandable clamp ring 830 a (for example a “Sannsaetze” available from Maedler GmbH, Germany) is placed over shaft 825 a and simultaneously inserted into circular opening 832 a in side support 740 a. Tightening the cap screws 831 a located about the periphery of clamp ring 830 a causes clamp ring 830 a to simultaneously expand inwards against shaft 825 a and outwards against the wall of opening 832 a, thus firmly and rigidly clamping side support 740 a to shaft 825 a. Loosening screws 831 a causes clamp ring 830 a to contract, allowing side support 740 a to be moved relative to shaft 825 a. Thus, the position of side support 740 a may be adjusted both rotationally and linearly with respect to shaft 825 a.

FIG. 8E provides a front elevation of the assembly shown in FIG. 8A with side support 740 a and clamp ring 830 a removed. As previously described, stop unit 840 a is keyed to and rotates with shaft 825 a. Stop unit 840 a is in front of and rotates relative to spacer 820 a, which is fixed relative to tumble/theta block 755 a. Screws 821 a and 822 a are threaded into spacer 840 a, and their heads protrude in front of spacer 820 a. Stop unit 840 a includes a partial-circular cut away region demarcated by radial transition portions 841 a and 842 a. Stop unit 840 a may rotate clockwise to the position illustrated where transition portion 841 a contacts the head of screw 822 a. Stop unit 840 a may similarly rotate counterclockwise until transition portion 842 a contacts the head of screw 821 a. As illustrated, transition regions 841 a and 842 a are approximately 180 degrees apart while screws 821 a and 822 a are located approximately 90 degrees apart. This results in approximately 90 degrees of rotation between the two stopped positions. The arrangement may be designed to provide other limits of rotation. The limits of rotation define the amount of tumble rotation that is provided to test head 110 when it is attached to side support 740 a. As illustrated, approximately 94 degrees of rotation are provided, allowing the test head to be manipulated from a vertical plus/minus two degrees position to a horizontal plus/minus two degrees position. Other ranges of motion may be desirable and can be readily designed in. For example, if screw 821 a is moved to the hole position 823 a, the test head would be limited to just a few degrees of tumble motion, similar to the situation discussed in the '048 patent previously referenced.

We now turn to FIGS. 9A, 9B, 9C, and 9D to describe theta carriage assembly 751 b and apparatus associated with it. FIGS. 9A and 9B provide perspective views from two different angles, and FIGS. 9C and 9D provide exploded views. Many of the details are the same as previously described with respect to the other theta carriage assembly 751 a and FIGS. 8A through 8D. Thus, it is only necessary to describe and discuss the significant differences between the two.

The first significant difference is that mid plate 758 b used with carriage assembly 751 b is more complex than mid plate 758 a used with carriage assembly 751 a. In particular, mid plate 758 b includes extension region 759 b, which includes threaded hole 799 b. Stepped timing belt pulley 982 is mounted to extension region 759 b by means of shoulder screw 989 which is passed through bearing 988 and received by threaded hole 799 b. It is significant to note that threaded hole 799 b is located so that it is coaxial with mid plate openings 766 b and 768 b, flange bearings 801 b and 803 b, and pivot journals 802 b and 804 b. Thus, tumble/theta block 755 b and stepped timing belt pulley 982 rotate about the same axis, which is axis 202 b in FIGS. 2A and 2B.

The second significant difference is that spacer 820 a and stop unit 840 a associated with carriage assembly 751 a are not included with carriage assembly 751 b. Instead of these components, gear box assembly 750 is utilized with carriage unit 751 b. (Note, no gear box assembly is incorporated with carriage unit 751 a). Gear box assembly 750 is attached to theta/tumble block 755 b with appropriate screws. As will be explained in more detail later, gear box 750 contains worm gear 920, which is driven by worm 970. Worm 970 is coupled to timing belt pulley 975 so that rotation of pulley 975 causes rotation of worm 970, which in turn causes rotation of worm gear 920. Shaft 825 b extends through worm gear 920 and is keyed to it with key 827 b. Side support 740 b is attached to shaft 825 b using expandable clamp ring 830 b in the same manner as side support 740 a is attached to shaft 825 a, previously described. Timing belt 980 couples inner step 983 of stepped pulley 982 to pulley 975. Idler pulley 986 engages timing belt 980 and may be adjusted to properly tension timing belt 980. Thus, rotation of pulley 982 causes rotation of pulley 975, worm gear 920, shaft 825 b, and ultimately side support 740 b. Side support 740 b may be rigidly attached to test head 110.

Side supports 740 a and 740 b are attached to test head 110 such that shafts 825 a and 825 b are coaxial, thereby defining tumble axis 201 previously discussed. It is therefore seen that rotation of pulley 982 will cause test head 110 to be rotated about axis 201.

FIGS. 10A, 10 b, and 10C illustrate the sliding attachment of a theta carriage assembly to a cradle arm. Base plate 780 a is attached to the inside of cradle arm 290 a with appropriate screws. Grooved linear rails 770 a are attached to base plate 780 a as shown with the groove of one rail 770 a facing up and the groove of the other rail 770 a facing down. Theta carriages 752 a and 754 a are attached to mid plates 756 a and 758 a as shown and as previously described. Theta carriage extension 730 a is attached to theta carriage 754 a. As is best shown in the exploded view of FIG. 10C, linear bearing assemblies 762 a are attached top and bottom to theta carriages 752 a and 754 a so that bearings 762 a are facing either upwards or downwards so as to engage the respective mating grooves of rails 770 a. Thus, theta carriage assembly 751 a is slidingly coupled to base plate 780 a. In a similar manner, theta carriage assembly 751 b is sliding coupled to base plate 780 b, which is in turn attached to the inside of opposite cradle arm 290 b.

When theta carriage assemblies 751 a and 751 b are so respectively coupled to cradle arms 290 a and 290 b, the common axis of pivot journals 802 a and 804 a defines axis 202 a, previously discussed with reference to FIGS. 2A and 2B. Similarly, the common axis of pivot journals 802 b and 804 b defines axis 202 b. As theta carriage assemblies 751 a and 751 b are linearly moved in opposite directions to provide “theta Y” rotation of test head 110, the distance between axes 202 a and 202 b changes slightly. This distance change must be accommodated in the mechanical structure. The amount of rotation is small, less than plus/minus 0.04 radians. The nominal distance between axes 202 a and 202 b is approximately one meter or less. It can be shown that the change in distance between axes 202 a and 202 b through 0.04 radians of rotation is approximately 1.6 mm. This may be accommodated by deflections of approximately 0.8 mm near the distal ends of each of the cradle arms 290 a and 290 b, or by allowing a slight linear play in the coupling of shafts 825 a and 825 b to their respective tumble/theta blocks 755 a and 755 b, or by a combination of both.

A locking mechanism is provided on each of the two cradle arms to enable an operator to lock test head 110 with respect to “theta Y” rotation with respect to the cradle's coordinate system 10. Lock handles 815 a and 815 b include threaded members (not visible), which extend through slots 291 a and 291 b in cradle arms 290 a and 290 b respectively. The threaded members further extend through slots 782 a and 782 b in base plates 780 a and 780 b respectively. Slots 291 a and 291 b are located generally directly above slots 782 a and 782 b respectively. The threaded members engage special nuts 811 a and 811 b, which in turn engage notches 812 a and 812 b in mid plates 756 a and 756 b respectively. Thus, by rotating lock handle 815 a in a first direction will cause it to contact the upper surface of arm 290 a, preventing sliding motion of theta carriage assembly 751 a. Rotating lock handle 815 a in the opposite direction releases the locking action. In a similar manner, sliding motion of carriage assembly 751 b may be locked or unlocked by using lock handle 815 b. It should be noted that with theta motion thus locked, tumble motion is not prevented.

The details regarding gear box 750 are more clearly shown in FIGS. 11A, 11B, 12A, and 12B. Refer also to FIGS. 9A, 9B, 9C, and 9D. Again, as shown, worm gear 920 is included. Worm gear 920 may be placed in opening 961 of housing 960 so that it is between cover plate 950 and housing 960. Worm gear 920 is mounted on and keyed to shaft 825 b (FIGS. 9A, 9 b, 9C, and 9D), which passes through opening 921. Thus, shaft 825 b, which is supported by bearings within tumble/theta block 755 b, supports worm gear 920. That is, worm gear 920 fits within opening 961, but is not in contact with or supported by housing 960.

Upper housing block 965 is attached to housing 960 with appropriate fasteners. Worm 970 abuts against and meshes with worm gear 920. Worm 970 is keyed to shaft 977 with key 971. Shaft 971 extends through flange bushings 973 inserted into openings in arms 969 of housing 960 and upper housing block 965. An appropriate timing belt pulley 975 may be keyed to shaft 977 with key 976 to facilitate rotation of worm 970. Rotation of worm 970, in turn, causes rotation of worm gear 920. As worm gear 920 rotates, shaft 825 b (shown in FIGS. 9C and 9D) rotates. As shaft 825 b rotates, side support 740 b rotates. In this manner, test head 110 rotates.

Worm 970 is coupled to pulley 975 by means of shaft 977. Rotation of pulley 975 causes rotation of worm 970. Pulley 975 rotates through the movement of timing belt 980. See FIG. 9B. Belt 980 is moved by the rotation of pulley 982. As will be described in more detail subsequently, pulley 982 is rotated by turning tumble drive handle 995 so that shaft 990 rotates.

Idler pulley 986 is mounted to upper housing block 965 by means of bearing block 982 and appropriate bearings (not visible). Bearing block 982 is attached to upper housing block 965 by means of screw 987. The axis 1901 of screw 987 is apart from (that is, not coaxial with) axis 1902 of idler pulley 986. Thus, when screw 987 is loosened, axis 1902 of idler 986 may be rotated about screw axis 1901. In this way, the periphery of idler 986 may be moved closer to or further from the periphery of pulley 975. This feature may be used to adjust the tension in timing belt 980. For example, idler 986 is first moved away from pulley 975. Timing belt 980 is then installed. Idler 986 is then moved closer to pulley 975, pressing against timing belt 980 and tensioning it. When the tension is appropriately adjusted, screw 987 may be securely tightened. It is seen that as tumble theta block 755 b pivots about its axis defined by pivot journals 802 b and 804 b, gear box 750 rotates with it. Because stepped pulley 982 is coaxial with the pivot axis, the distance between gear 982 and pulley 975 remains constant as gear box 750 pivots. Thus, the proper tension in belt 980 will also desirably remain constant as gear box 750 pivots.

FIG. 12A provides a side view of gear box 750, defining the location of vertical section B-B. Sectional view B-B is provided in FIG. 12B. It has already been described how worm 970 is attached to shaft 977 which passes through flange bushings 973 in openings contained in arms 969 of housing 960. Thus, worm 970 is fitted between arms 969 of housing 960. Worm 970 is separated from arms 969 by two stacks of Belleville washers 979 (also known as cupped spring washers; see http://en.wikipedia.org/wiki/Belleville washer for more details) that are inserted onto shaft 977. The stacks of Belleville washers are arranged to form two compression springs between worm 970 and arms 969, allowing worm 970 to be linearly movable toward either of the two arms 969. In forming the springs, the washers 979 are stacked with cups facing in alternating directions. The two stacks contain equal numbers of washers. When gear box 750 is assembled, both stacks are partially compressed. Thus, each stack exerts nominally the same force on worm 970, nominally positioning it centrally between arms 969. With test head 110 driven to a desired tumble angle, an external force applied to test head 110 may cause a moment about tumble axis 201. Test head 110 may rotate about the tumble axis slightly in response to such an external force. In particular the external force causes shafts 825 a and 825 b to attempt to rotate. Worm gear 920 thus attempts to rotate; in doing so it exerts a force on worm 970 in its axial direction. Because the gear ratio between worm gear 920 and worm 970 is such that back driving is prevented, worm 970 is urged in a linear direction along its axis. This causes one of the two stacks of Belleville washers to contract and the other to expand. Motion may continue until the contracting stack has completely flattened (that is, bottomed out). When the external force is removed, worm 970 is urged back to its nominal central position by the contracted Belleville washer stack which defines a biasing assembly. Thus, compliance about the tumble axis is provided.

With the aid of FIGS. 13A, 13B, 14A and 14B, the coupling of tumble drive handles 280 a and 280 b to gear box 750 is described. FIG. 13A provides an oblique view of the interior of assembled cradle arm 290 b, which includes tumble-drive handles 280 a and 280 b. FIG. 13B shows tumble-control-side carriage extension assembly 1400 exploded away from the interior of cradle arm 290 b. Also, to provide some visibility, upper lip 2901 b of arm 290 b has also been exploded away. FIGS. 14A and 14B provide more detailed views of carriage extension assembly 1400.

Tumble drive handles 280 a and 280 b are keyed to shaft 1910 which passes through a hole or channel in structural block 1925. Appropriate bearings, for example bearing 1926, are utilized so that shaft 1910 may rotate freely. Timing belt pulley 1915 is also keyed to shaft 1910. Long timing belt 1980 is shown coupling pulley 1915 to outer step 984 of stepped pulley 982. (The coupling of inner step 983 of stepped pulley 982 to pulley 975 and worm 970 has been previously described.) Thus, rotation of either tumble drive handle 280 a or 280 b causes rotation of shaft 1910 and pulley 1915 (as well as the other tumble drive handle). This rotation is coupled to stepped pulley 982 by means of long timing belt 1980 and subsequently, by means previously described, to worm 970 and worm gear 920, shaft 825 b, side coupling 740 b, and, finally, test head 110.

Structural block 1925 is secured to theta carriage extension 730 b by means of screws 1945, which pass through slots 1946 in carriage extension 730 b. Tensioning block 1940 is also secured to extension carriage 730 b with screws 1947. Adjustment bolt 1941 is threaded through a tapped through-hole in tensioning block 1940. The head of adjustment bolt 1941 bears against structural block 1925. Check nut 1942 is provided, and it may be tightened against tensioning block 1940 to maintain adjustment bolt 1941 in a desired position. Thus, the tension in timing belt 1980 may be adjusted by first loosening check nut 1942 and screws 1945. Tensioning bolt 1941 may then be rotated so that its head motion causes shaft 1910 to move inwards or outwards, thus loosening or tightening belt 1980 respectively. When the desired tension is achieved, screws 1945 and check nut 1942 are securely tightened.

It is noted that because structural block 1925 is attached to theta extension carriage 730 b that the two move as a single unit when the theta Y orientation of test head 110 is adjusted. Consequently, the distance between pulley 1950 and stepped pulley 982 remains constant throughout theta Y motion, maintaining a constant tension in timing belt 1980.

It is noted that the tumble drive mechanism includes four pulley wheels and two drive belts in addition to a worm and worm gear. The ratios of pulley wheel diameters to one another as well as the gear ration between the worm and worm gear are selected so that tumble drive handles are easy for an operator to turn while requiring a reasonably small number of full turns to move test head 110 through its approximate 90 degrees of motion. Of course, the sizes and costs of the various components is also a consideration in their specification and selection.

Extension carriage assembly 1400 also includes linear bearings 1921 and 1922, which are attached to structural block 1925. Linear bearings 1921 and 1922 engage linear rails 1923 and 1924, which may be secured to the inner wall of cradle arm 290 b. Thus, when carriage assembly 1400 is moved inwards or outwards (for example during a theta Y adjustment of test head 110), linear bearings 1921 and 1922 glide along rails 1923 and 1924. This arrangement may provide structural support for the tumble drive mechanism just described. In particular, carriage extension 730 b may be constructed of a lightweight material that may be subject to twisting or buckling under the forces imposed by the tension in long timing belt 1980 and/or the rotation of tumble-drive handles 280 a and 280 b. Inclusion of linear bearings 1921 and 1922 and rails 1923 and 1924 may mitigate the effects of such forces. In an exemplary embodiment of the invention, such bearings and rails are not incorporated in conjunction with the other carriage extension 730 a, which does not have an associated tumble drive mechanism.

We now return attention to the theta drive mechanism. The apparatus that enables an operator to rotate test head 110 about a Y axis through the rotation of, for example, theta drive handle 270 b has been described in detail. The ultimate limit in such theta motion is defined when one of or both tumble/theta blocks 755 a and 755 b contacts a theta carriage 752 a, 754 a, 752 a, and/or 754 b respectively. However, this may not be a desirable situation, because to achieve such a position one of springs 710 a, 714 a, 710 b, and 714 b must be fully compressed to drive the tumble theta block into such contact. Thus, there would be no “wiggle room” or compliance available for subsequent maneuvers, such as docking. Thus, it may be desirable in certain applications to put limits on how much rotation from the zero position (that is, where axis 201 if parallel to the X axis) can be provided by rotating a theta drive handle 270 a or 270 b. This, in turn, is desirably an amount that does not cause any compression of springs 710 a, 714 a, 710 b, and 714 b and leaves enough rotation space available for compliant motion against the full range of available compression/extension of springs 710 a, 714 a, 710 b, and 714 b.

FIGS. 15A, 15B, and 15C illustrate a theta-drive stop mechanism that provides such a theta drive limit. This mechanism may be optionally included depending upon circumstances. FIG. 15A shows the interior of cradle arm 290 b with extension carriage 1400 and upper lip 2901 b removed. FIG. 15B shows a close up of particular features of interest. FIGS. 15A and 15B have been derived from the exploded view of FIG. 13B. Visible in FIG. 15A are pillow block 630 b, shaft 250 b, coupling 255 b, threaded member 260 b, nut 702 b, cylindrical nut extension 704 b, springs 710 b and 714 b, and anti-rotation block 716 b, all having been described earlier. Also, as described previously, as theta drive handle 270 b and shaft 250 b are rotated, cylindrical nut extension 704 b moves linearly inwards and outwards. In order to limit the amount of theta motion that is available by rotation of a theta drive handle 270 b (or 270 a), stop block 1300 and stop screw 1310 are provided. (Stop screw 1310 is also indicated in FIG. 3B.) Stop screw 1310 is a socket head cap screw that is threaded into a tapped hole in the surface of nut extension 704 b. In FIG. 15B, a portion of the head of screw 1310 is visible. Screw 1310 and the hole that it is threaded into are orientated so that the axis of screw 1310 is perpendicular to the inside wall of cradle arm 290 b. Stop block 1300 is shown in more detail in FIG. 15C, and it is attached with bolts and nuts to the inner wall of cradle arm 290 b such that stop slot 1305 may receive the head of screw 1310 and such that slot 1305 is parallel to the axis of travel of nut extension 704 b. Thus, the linear travel of nut extension 704 b is limited to the length of slot 1305 minus the diameter of the head of screw 1310. The length of slot 1310 is thusly designed to correspond to the maximum amount of drivable theta motion desired in the system. Stepped slots 1307 are provided in stop block 1300 to facilitate adjustable mounting. Mounting hex nuts are captured in stepped slots 1307 and corresponding bolts extend through holes in the side of cradle arm 290 b. Thus, stop block 1300 may be adjusted inwards and outwards by loosening the bolts, and fixed in a desirable position by tightening the bolts.

FIGS. 1A through 15C have thus described the components located within cradle 200 corresponding to an exemplary embodiment of the invention. There are three minor variations to this embodiment which thus far may not have been described.

The first variation concerns the theta lock handles. Theta lock handles 815 a and 815 b may be round as shown, for example, in FIGS. 10A, 13B, and 15A or “L”-shaped as illustrated, for example, in FIGS. 1A through 2B. Other shapes may also be used as well. The particular shape may be selected in accordance with the preferences of particular users of the equipment.

The second variation concerns the inclusion of auxiliary handle 2910, which is included in FIGS. 13A, 13B, and 15A. Auxiliary handle 2910 is provided for the use of operators in manually positioning test head 110. It is accordingly an option. Its presence and location are determined by particular user requirements.

The third variation concerns the number of theta drive handles. FIGS. 1A through 4A all show cradle 200 having two theta drive handles 270 a and 270 b. However, it was shown and discussed that only one theta drive handle is necessary. Thus, FIG. 16 illustrates a cradle 200 having a single theta drive handle 270 b. Slot 690 a is devoid of a theta drive handle in comparison to the other embodiments studied. The shaft that would connect to a drive handle has been shortened so that it does not extend through slot 690 a. Obviously, slot 690 a could also be eliminated.

As yet another item to be emphasized, compliance in tumble and theta degrees of freedom has been discussed. However, due to springs 710 a, 710 b, 714 a, and 714 b compliance in the “In-Out” degree of freedom is also provided. Thus, if test head 110 is pushed “Out” towards the closed end of cradle 200, springs 710 a and 710 b would compress, providing linear motion compliance. Similarly, if test head 110 is pushed “In” towards the open end of cradle 200, springs 714 a and 714 b would compress, again providing linear motion compliance. Thus, the invention provides driven motion in two degrees of freedom and compliance in three degrees of freedom.

Still another point to be made is that although the illustrated embodiment uses handles to allow manual positioning of a test head in theta Y and Tumble degrees of freedom, it is also feasible to substitute motors or other contrivances for the handles. In this way an operator could manipulate the test head in these axes by push button control. Further, with the addition of a controller or a control computer, test head manipulation could thus be automated.

Referring to FIGS. 17A through 19J, a cradle 1200 that is an alternative embodiment of the invention will be described. Cradle 1200 is similar to cradle 200 previously described above. Both cradles 200 and 1200 provide theta (or yaw), tumble (or pitch), and in-out compliance, which allow relatively small external forces to simultaneously adjust (or fine tune) the position of the load in those three degrees of freedom. Cradle 1200 is configured to provide tumble motion over a smaller range compared to the tumble motion range of cradle 200.

As shown in FIG. 17A, cradle 1200 has essentially the same cradle shape and structure as cradle 200, which may be scaled as appropriate to a specific situation. This shape facilitates room for cables and cooling ducts as the test head in maneuvered through its motion envelope. Further, theta drive handles 1270 a and 1270 b, shafts 1250 a and 1250 b, belt 1222 and associated hardware are of the same design, function and purpose as theta drive handles 270 a and 270 b, shafts 250 a and 250 b, and belt 222 described previously with respect to the first embodiment.

In the present embodiment, cradle arms 1290 a and 1290 b, see FIGS. 17A and 17B, include square tubing members 1291 a and 1291 b for reinforcement. Additionally, bearing blocks 1631 a and 1631 b, which are secured to cradle arms 1290 a and 1290 b respectively, have been added for providing additional support to shafts 1250 a and 1250 b, respectively. This additional support is necessitated by other design differences between the two embodiments, which will be described later.

Cradle arms 1290 a and 1290 b include openings 1293 a and 1293 b near these distal ends. These may be covered by removable covers 1292 a and 1292 b respectively. FIG. 17A shows cover 1292 b installed to cover opening 1293 b, which is thus not visible. FIG. 17B, however, shows cover 1292 a separated from arm 1290 a, exposing opening 1291 b. Opening 1291 b and what lies behind it is shown in closer detail in FIG. 17C. The rear of carriage plate 1750 a is thus visible. FIG. 17C will be returned to later in conjunction with a discussion about carriage assembly 1751 a and carriage assembly 1751 b. The details visible through opening 1293 b in arm 1290 b are essentially the same and will not be described in any amount of detail.

FIG. 17D shows more clearly the details of the connection between theta drive handle 1270 a and carriage assembly 1751 a (which will be described in more detail later). In forming this figure, the cradle structure has been removed from view for clarity. Thus, as previously described with respect to FIGS. 3A through 5, theta drive handle 1270 a is attached to shaft 1250 a, which is coupled via flexible coupling 1255 a to threaded shaft 1260 a. Threaded shaft 1260 a is threaded into cylindrical nut 1702 a, which is rigidly attached to hollowed cylindrical nut extension 1704 a. Cylindrical nut extension 1704 a is of the same type as the previously described nut extensions 704 a and 704 b. In particular, it includes extension member 1706 b having a threaded portion 1708 a at its distal end. These are not shown in FIG. 17D, but are the same as items 706 b and 708 b in FIG. 5.

Also, similar to the previously described embodiment, shaft 1250 a is coupled to crisscrossed belt 1222, which is in turn similarly coupled to shaft 1250 b, associated with cradle arm 1290 b. Thus, as previously described with respect to the first embodiment, rotation of shaft 1250 a in a first direction causes rotation of shaft 1250 b in the opposite direction and vice versa.

Shaft 1250 a is supported by pillow block 1630 a, which is configured to prevent linear motion of shaft 1250 a along its axis of rotation; however, in contrast to the first embodiment, additional bearing block 1631 a has been added to provide additional support. In relation to the first embodiment, large carriage extension 730 a has been removed and functionally replaced by carriage connector 1730 a. Whereas carriage extension 730 a of the first embodiment provides structural support for shaft 1250 a and it associated apparatus, connector 1730 a provides less support. Thus, bearing block 1631 a is included to provide the needed support.

The connection between nut extension 1704 a and carriage assembly 1751 a is now described. First, referring to FIGS. 18A and 18B, carriage assembly 1751 a includes base plate 1780 a, which may be attached to the inside of cradle arm 1290 a by suitable screws 1294 a (FIG. 17B). When base plate 1780 a is so installed, its included opening 1781 a aligns with arm opening 1293 a. Carriage plate 1750 a is slidingly coupled to base plate 1780 a by means of linear bearing assemblies 1760 a.

Referring to FIG. 17D, right angle member 1722 a is connected to machined recess 1537 a in carriage plate 1750 a with suitable screws or the like. Carriage connector 1730 a is formed from a suitable material such as steel and has opposing right angle sections 1723 a and 1724 a at each end formed by bending or other suitable means. Right angle section 1723 a is attached to right angle member 1722 a by suitable means such as screws. Right angle section 1724 a includes a hole somewhat larger in diameter than extension member 1706 a, which extends from nut extension 1704 a. Right angle member 1716 a includes a hole tapped to receive threaded end 1708 a of extension member 1706 a. Right angle section 1724 a is compliantly assembled to extension member 1706 a as follows. First, compression spring 1710 a is fitted over extension member 1706 a followed by right angle section 1724 a, which is in turn followed by second compression spring 1714 a, thereby providing a biasing assembly. Right angle member 1716 a is next held adjacent to the inside of carriage connector 1730 a, and threaded end 1708 a of extension member 1706 a is screwed into its tapped hole, desirably causing springs 1710 a and 1714 a to compress. Lock nut 1720, in combination with a suitable washer, is then tightened onto the end of threaded end 1708 a, preventing rotation of nut 1702 a and nut extension 1704 a from rotating. Right angle member 1716 a is not fixed to carriage connector 1730 a and may move relative to it. Accordingly, with nut 1702 a in a fixed position, carriage plate 1750 a may be moved linearly a small amount by an external force acting against springs 1710 a and 1714 a, providing compliance. The amount of compliance in terms of force and distance being determined by the characteristics selected for springs 1710 a and 1714 a for the particular application. Additionally, and in a similar fashion to the first embodiment, rotation of shaft 1250 a causes nut 1702 a to move linearly along threaded shaft 1260 a, which in turn causes carriage plate 1750 a to move linearly along the path defined by rails 1770 a. While not shown, the present embodiment may include a theta-drive stop mechanism as previously described with respect to the first embodiment (FIGS. 15A through 15C). Such a stop mechanism may, of course, be optionally included, depending upon circumstances.

A similar mechanism to that just described is provided on cradle arm 1290 b for providing driven and compliant linear motion of carriage plate 1750 b associated with carriage assembly 1751 b. Further description, therefore, is not necessary.

Just as in the first embodiment, a test head may be held within cradle 1200 by securing its sides to side supports 1740 a and 1740 b, which are included in carriage assemblies 1751 a and 1751 b, respectively. Rotation of either of theta drive handles 1270 a and 1270 b causes carriage plates 1750 a and 1750 b to move linearly in opposite directions along paths determined by linear rails 1770 a and 1770 b, which are also included in carriage assemblies 1751 a and 1751 b, thus providing theta motion in positioning the supported load. Also as in the first embodiment, due to the compliant nature of the coupling between nut extensions 1704 a and 1704 b and respective carriage plates 1750 a and 1750 b, compliance in the theta and in-out degrees of freedom is provided.

Also, as will be described below, carriage assemblies 1751 a and 1751 b include spherical bearings to provide rotational degrees of freedom to side supports 1740 a and 1740 b to allow tumble and theta motion of the supported load.

Referring to FIGS. 18A through 18C as well as FIG. 17C, carriage assembly 1751 a, which includes carriage plate 1750 a, is further described. As stated above, carriage assembly 1751 a includes base plate 1780 a, which may be attached to the inside of cradle arm 1290 a by suitable screws 1294 a (FIG. 17B). In the figures, carriage plate 1750 a is shown at approximately the center of its range of linear travel. Previously described right angle member 1722 a may be connected to machined recess 1537 a in carriage plate 1750 a with suitable screws. Carriage plate 1750 a also includes machined recesses 1535 a and 1536 a, but these are not used in carriage assembly 1751 a. This is because carriage plate 1750 a has been designed for multiple applications, some of which may require these additional recesses.

Referring again to FIGS. 18B and 18C, stepped tumble shaft 1510 a (shown in detail in FIG. 19J) is fitted into counter-bored opening 1535 in side support 1740 a such that shaft head 1514 a is nominally slightly below surface 1536. This is a slip fit allowing shaft 1510 a to move slightly with respect to side support 1740 a, thus providing adjustment for sight variations in the widths of supported loads. Large diameter portion 1513 a of stepped tumble shaft 1510 a is longer than side support 1740 a is thick, so that step 1512 a will be a distance away from the rear of side support 1740 a. Spherical bearing unit 1520 a is press fitted into opening 1522 a of base plate 1750 a. Spherical bearing unit 1520 a includes opening 1521 a, which receives small diameter end 1511 a of stepped tumble shaft 1510 a. Thus, stepped tumble shaft 1510 a may be inserted into bearing unit 1520 a to the depth determined by the location of step 1512 a. When fully inserted, the end 1516 a of stepped tumble shaft 1510 a does not extend outside of spherical bearing unit 1520 a. Stepped shaft 1510 a may then be secured in place with washer 1518 a and socket-head cap screw 1517 a, accessible through openings 1293 a in arm 1290 a and 1781 a in base plate 1780 a. This arrangement serves to secure side support 1740 a securely to carriage plate 1750 a in a manner that allows side support 1740 a to rotate in three degrees of freedom relative to carriage plate 1750 a. Notice that once the load is secured to both side supports 1740 a and 1740 b, one of these degrees of freedom will become constrained.

Load attachment screws may be passed through two circular through-holes 1534 a and two slotted through-holes 1533 a in side support 1740 a in order to fasten the load to side support 1740 a. Slotted through-holes 1533 a are included to simplify the task of manually aligning the cradle 1200 to a heavy and awkward load. Side support 1740 a may be positioned so that the four through-holes 1533 a and 1533 b are aligned with four relatively large through holes 1538 a in carriage plate 1740 a, thus enabling access through openings 1293 a in arm 1290 a and 1781 a in base plate 1780 a.

As shown, side support 1740 a includes step 1741 a having step surface 1532 a. Step surface 1532 a is located at approximately the center of stepped tumble shaft 1510 a. Lock block 1575 a includes constant-radius cutout 1574 a, which desirably may be slightly less than, but no more than a semicircle and having a radius substantially the same as the radius of the large diameter portion 1513 a of tumble shaft 1510 a. Lock block 1575 a is installed so that the surface of cutout 1574 a is in contact with the exposed area of large diameter portion 1513 a of stepped tumble shaft 1510 a and fastened in place to step surface 1532 a with screws 1571 a. Desirably the dimensions are arranged so that nominally there is a small gap between step surface 1532 a and lock block 1575 a that is narrowed as screws 1571 a draw the two together. In this manner side support 1740 a and its attached load become locked to stepped tumble shaft 1510 a, preventing rotational movement of one relative to the other and also preventing linear motion of side support 1740 a along the length of stepped tumble shaft 1510 a.

Referring to FIGS. 19A through 19J, a description of carriage assembly 1751 b, which includes a mechanism for adjusting a position of rotation about a tumble axis and allowing compliance, will be described. Approximately +/−2.8 degrees of manually (or mechanized) adjustment is provided. Also, approximately +/−1.5 degrees of compliant tumble motion (driven by an external force) is also provided.

FIG. 19B shows carriage assembly 1751 b partially exploded into three major subassemblies: basic carriage 1592, side support unit 1594, and tumble adjuster 1596.

Basic carriage 1592 includes base plate 1770 b, carriage plate 1750 b, linear rails 1770 b and linear bearing assemblies 1760 b, which are the same as and have the same functions as their counterparts 1770 a, 1759 a, 1770 a, and 1760 a that are included in the previously described carriage assembly 1751 a.

Side support unit 1594 includes side support 1740 b, which is similar to side support 1740 a. In particular, it includes through-holes 1534 b and slotted through-holes 1533 b, arranged in a similar pattern as their counterparts 1534 a and 1533 a respectively are arranged on side support 1740 a. Appropriate screws passed through these holes attach one side of the load to side support 1740 b as previously described with respect to side support 1740 a. However, whereas, side support 1740 a of carriage assembly 1751 a includes a step located at approximately the center of hole 1535 a, side support 1740 b includes a narrow flange 1742 b at its lower edge. Also included in unit 1594 is stepped shaft 1510 b, which is shown in detail in FIG. 19J. Stepped shaft 1510 b includes two features not included in stepped shaft 1510 a. These are precisely machined press fit region 1508 b and retaining ring grove 1509 b. Stepped shaft 1510 b is press fitted into hole 1535 b of side support 1740 b (FIGS. 19C and 19D) by means of region 1508 b.

Tumble mechanism 1596 includes knob 1550 that an operator may turn to make small adjustments to the rotation of the load about the tumble axis in order to nominally planarize the load with respect to another apparatus. It also provides compliance so that a force acting directly on the load may rotate it about the same tumble axis.

Tumble mechanism 1596 includes compliance block 1570, which includes opening 1572. IGUS flange bearing 1579 is press fit into opening 1572. Step shaft 1510 b may be inserted into bearing 1579 so that the portion of large diameter section 1513 b that extends out of side support 1740 b is fitted into bearing 1579. Compliance block 1579 and side support 1740 b may thus be rotatably coupled in close proximity to one another. A retaining lock ring (not shown for clarity) may be inserted into groove 1509 b in large diameter portion 1513 b that extends beyond compliance block 1572 to hold the two units together.

The foregoing assembly comprising tumble mechanism 1596 coupled to side support unit 1594 may be rotatably coupled to basic carriage 1592. To do so, small diameter portion 1511 b of stepped shaft 1510 b is inserted into opening 1521 b of spherical bearing 1520 b, which is fitted into carriage plate 1780 b.

Thus, stepped tumble shaft 1510 b may be inserted into bearing unit 1520 b to the depth determined by the location of step 1512 b. When fully inserted, the end 1516 b of stepped tumble shaft 1510 b does not extend outside of spherical bearing unit 1520 b. Stepped shaft 1510 b may then be secured in place with washer 1518 b and socket-head cap screw 1517 b, accessible through openings 1293 b in arm 1290 b and 1781 b in base plate 1780 b. This arrangement serves to secure side support 1740 b securely to carriage plate 1750 b in a manner, which allows side support 1740 b to rotate in three degrees of freedom relative to carriage plate 1750 b. Notice that once the load is secured to both side supports 1740 a and 1740 b, one of these degrees of freedom will become constrained.

Two pins 1573 are fitted to receiving holes in compliance block 1570. These pins 1573 engage slots 1782 b in carriage plate 1780 b. Slots 1782 b are parallel to rails 1770 b. The width of slots 1782 b is merely a few thousandths of an inch greater than the diameter of pins 1573. Thus, compliance block 1570 is prevented from rotating about axis 1201 but is free to rotate about axis 1202 b (see FIGS. 17A and 17B).

Socket-head setscrew 1571 may be threaded into through hole 15711 in compliance block 1570 such that the socket head faces carriage plate 1780 b. Setscrew 1571 may be tightened against side support 1740 a, thus serving to lock side support 1740 a from rotating relative to compliance block 1570 and carriage plate 1750 a. Through hole 15711 is aligned with slot 1781, which passes through carriage plate 1750 b. Thus, a user can access setscrew 1571 with an appropriate Allen wrench through the access provided by arm opening 1293 b and the corresponding opening in base plate 1780 b. It is contemplated that an extended length screw would pass through carriage plate 1750 a, base plate 1780 a and a suitable opening in arm 1290 b. Such an extended length screw could have a handle or other actuator attached to it to operate the screw as a locking device.

When a load is coupled between side plates 1740 a and 1740 b such that side plates 1740 a and 1740 b are parallel with one another, the axes of stepped shafts 1510 a and 1510 b will preferably be aligned, defining axis 1201 (FIG. 17A). Compliance block 1570, which is not allowed to rotate about axis 1201 due to the interaction of pins 1573 with carriage plate 1750 b, limits the amount that side plate 1740 b (and hence the attached load) may rotate due to its interaction with flange 1742 b. This interaction is constrained by the control and compliance apparatus, which will be discussed in the following paragraphs and with the aid of exploded views in FIGS. 19B through 19D and the cross section view in FIG. 19I.

Two holes 1599 a and 1599 b are formed in compliance block 1570. Each has an upper portion 1571, which is threaded. Each also has a lower portion 1572, which is not threaded and having larger diameter. Threaded end 1551 of adjustment shaft 1555 is threaded into first threaded hole 1599 a. Drive gear 1562 a is attached to adjustment shaft 1555 with a setscrew that engages flat 1552. Knob 1550 (or other suitable handle or actuator) is attached to the distal end of shaft 1555 to allow an operator to screw shaft 1555 inwards or outwards with respect to compliance block 1570. Similarly, driven follower shaft 1558 has threaded end 1559 threaded into threaded upper portion 1571 of hole 1599 b. Also gear 1562 d is secured to shaft 1558 with a suitable setscrew at flat 1557. Intermediate idler gears 1562 b and 1562 c are mounted to compliance block with shoulder screws 1561 as shown. Idler gears 1562 b and 1562 c may freely rotate about their respective shoulder screws 1561. The four gears 1562 a through 1562 d are arranged so that rotation of adjustment shaft 1555 in a first direction causes rotation of driven follower shaft 1558 in the opposite direction. Thus, as adjustment screw 1555 is screwed inwards into compliance block 1570, driven follower screw 1558 is screwed outwards, and vice versa. Of course, as the screws move linearly, drive gear 1562 a and driven gear 1562 b also move linearly with them. However, the amount of linear motion required is relatively small, and both will stay in mesh with their respective idler gears 1562 b and 1562 c.

Flanged, threaded compression inserts 1574 are inserted into the lower, unthreaded portion 1572 of holes 1599 a and 1599 b. Inserts 1574 are sized so that they may move relatively freely within holes 1599 a and 1599 b. The details of inserts 1574 are shown in FIG. 19H. Each may be formed from a solid piece of material, preferably metal, by turning a cylindrical body 15742 of a diameter compatible with a sliding fit within hole portion 1572, and a flange portion 1575 of a diameter larger than hole portion 1572. As will be described below, flange portion 1575 will interact with Bellville washers 1576 and preferably should be approximately the same diameter. Threaded hole 15744 is drilled and tapped from the flange end to a depth that leaves a solid, flat end 15741. The length of inserts 1574 is such that when adjustment screw 1555 and driven follower screw 1558 are both inserted equal amounts into compliance block 1570, flat ends 15744 will be in contact with their respective screws 1555, 1558 and their flanges will be at a distance from the lower surface of compliance block 1570.

Two counter-bored, slotted holes 1744 b are included in flange 1742 b of side support 1740. Slotted holes 1744 b are aligned with compliance-block holes 1599 a and 1599 b. Slotted holes 1744 b are oriented so that their slots are perpendicular to the axis of stepped screw 1510; that is, the slots are perpendicular to tumble axis or rotation 1202. A spherical swivel washer 1578 set is placed at each counter-bored hole with the spherical surface facing the flat counter bore. A stack of Bellville spring washers 1576, arranged to form a compression spring is placed between each swivel washer 1578 and the flange of its respective compression insert 1574, thereby providing a biasing assembly. Shoulder screws 1580 are inserted through slotted holes 1744 b, pass through the stack of swivel washers 1578 and Bellville washers 1576, and threaded into their respective threaded holes 15744 of inserts 1574 so that their shoulders are tight against their respective flanges 1575.

When properly assembled, Bellville washer stacks 1576 are in equal compression between their respective spherical swivel washers 1578 and respective insert 1574 flanges 1575 with screws 1555 and 1558 inserted to equal depths. In this nominal position flange 1742 b of side support 1740 b should nominally be parallel to arm 1290 b and rails 1770 b. A force applied to a load coupled to side support 1740 b in a direction to cause a moment about axis 1202 will cause the load to rotate about axis 1202. As it does so, one Bellville washer set will compress while the other set expands. When the force is removed, the imbalance between the two washer sets (which act as compression springs) will urge the system back towards its nominal position. Thus, the system posses a compliant characteristic in that it allows an external force to move the load as well as a resilient characteristic in that the load tends to return to a nominal position when the force is removed. In practice, when a load is installed between the two side supports 1740 a and 1740 b, its center of gravity will be displaced somewhat from axis 1202, causing a moment about axis 1202 rotating the load away from a desired orientation. By rotating knob 1550 an operator can adjust the forces on the Bellville washer stacks, moving the load back to a desired position. In other cases, the load's center of gravity may be reasonably coincident with axis 1202; here an operator may again adjust the position of the load by rotating know 1755.

Referring to FIGS. 20A through 25A, cradle 2200 that is a third embodiment of the invention will be described. As in the previous embodiments, cradle 2200 includes opposed arms 2290 a and 2290 b joined by a rear portion 2209. Cradle 220 provides driven tumble motion of approximately plus/minus 90 degrees combined with tumble compliance of plus/minus approximately two or three degrees. This is combined with a driven theta adjustment and theta compliance of plus/minus approximately three degrees and in-out compliance of plus/minus approximately five mm. Thus, at the rear of the cradle are theta drive handles 2270 a and 2270 b. Also at the rear of the cradle is tumble drive handle 2280.

Arms 2290 a and 2290 b include interior plates 2295 a and 2295 b, which provide extra strength and rigidity as well as a protective covering of portions of the theta drive apparatus. Access to the rears of carriage assemblies 2751 a and 2751 b is provided by arm openings 2293 a and 2293 b respectively. Suitable cover plates (not shown in the Figures) may be provided to cover openings 2293 a and 2293 b. Arms 2290 a and 2290 b also include end covers 2296 a and 2296 b respectively. Arm 2290 b includes a tumble apparatus to be described below. This apparatus is partially hidden by covers 2297 and 2298. In various figures, interior plates 2295 a and 2295 b, end covers 2296 a and 2296 b and tumble covers 2297 and 2298 are removed for clarity.

The theta driving mechanism is essentially the same as described with respect to the first two embodiments, particularly the second embodiment. Thus, only the differences will be mentioned. FIG. 20C is a partially exploded view of arm 2290 b with the aforementioned plates and covers removed. Carriage assembly 2751 b is thus revealed. It is essentially the same as carriage assembly 1751 b of the second embodiment. As in the second embodiment, spherical bearing 2721 b is fitted into an opening in carriage plate 2750 b. However, no additional through holes, openings or slots are required in carriage plate 2750 a as they are in carriage plates 1751 a and 1751 b. However, the three machined recesses shown on the periphery of carriage plates 1751 a and 1751 b are shown to be also present on carriage plates 2751 a and 2751 b. Connected to an end machined opening is carriage connector 2730B; it and the apparatus connected to it are the same as in the second embodiment except for the bearings, which mount shaft 2250 b to the cradle.

Side support 2740 b is coupled to spherical bearing 2721 b by means of stepped shaft 2510. Stepped connecting shaft 2510 has a first end 2521 turned to a diameter to couple with spherical bearing 2721 b and a second end 2513 turned to a diameter suitable for insertion in hole 2534 in side support 2740 b. Between the two ends is large diameter region 2511, which serves to limit the insertion distance of end 2521 in spherical bearing 2721 b, and to provide a surface against which side support 2740 b may bear and freely rotate. Side support 2740 b includes two holes 2533 that may be used to attach the load with suitable screws. Side support 2740 b also includes tumble drive arm 2742. As will be described in more detail below, drive arm 2742 is connected with turn buckle 2415 to tumble traveler 2420, which moves linearly along lead screw 2430, thus causing side support 2740 b to rotate.

The interior of the square tube forming the rear 2209 of the cradle is shown in FIG. 21A, which is a sectional view taken at 21A-21A of FIG. 20B. FIG. 21B is the same but viewed from a small angle from the front and below to provide a useful perspective. FIG. 21A illustrates theta drive handle 2270 b coupled to shaft 2250 b, which in turn is coupled to threaded shaft 2260 b by means of coupler 2255 b. Threaded shaft 2260 b drives nut 2702 b and nut extension 2704 b, which are compliantly coupled, by means including spring 2710 b, to carriage coupler 2730 b and hence carriage plate 2250 b. This is, thus, the same structure as was described in the second embodiment. The difference is that in the present embodiment, shaft 2250 b is supported by bearings 2632 b and 2633 b, attached to interior faces of rear tube 2209, rather than by pillow blocks or bearings attached to the cradle's sidewall. Pulley 2635 b is attached to shaft 2250 b and is used to couple shaft 2250 b with a similar shaft within arm 2290 a by means of a suitable belt (not shown).

Carriage assembly 2751 a in arm 2290 a is the same as the foregoing; with the exception that side support 2740 a does not include a tumble drive arm (such as tumble drive arm 2742 included in side support 2240 b). Thus, a load may be attached between side supports 2740 a and 2740 b in a manner similar to the previous two embodiments. The two shafts 2250 a (not shown) and 2250 b are coupled with a belt (not shown) arranged as a figure eight so that rotation of either shaft 2250 a or 2250 b by means of theta drive handle 2270 a or 2270 b respectively causes the other shaft to rotate in the opposite direction, thereby causing carriage plates 2780 a and 2780 b to move linearly in opposite directions. Because cradle rear 2209 is straight and at right angles to sides 2290 a and 2290 b, the path between the two pulleys is straight and parallel to cradle rear 2209. Thus additional idler pulleys to guide the belt are neither needed nor included as in the previous two embodiments.

We now turn to describing the compliant tumble drive mechanism. First, with reference to FIG. 21B in particular, linear rail 2470 is attached to the bottom of cradle arm 2470. Angle bar 2410 is coupled to carriage plate 2450 b by corner brace 2405, which is screwed to the machined recess located on the lower edge of carriage plate 2750. Thus, angle bar 2750 moves linearly as carriage plate 2750 b moves linearly. Tumble drive handle 2280 is attached to shaft 2450, which is coupled by bearings and bearing blocks 2452 a and 2452 b to the bottom of cradle arm 2290 b. Shaft 2450 is also coupled to angle bar 2410 by means of bearings and bearing blocks 2454 and 2456 a. Shaft 2450 may rotate freely and move linearly along its axis with respect to bearing 2452 a and 2452 b. However, shaft 2450 is constrained to only rotate with respect to bearings 2454 and 2456 a by means of appropriate retraining clips, etc., which may be located at bearing 2456 a (for example, by the same techniques previously described with respect to the first embodiment for constraining shaft 250 b). Thus, shaft 2450 may not move linearly along its axis with respect to angle bar 2410.

Shaft 2450 is coupled to threaded lead screw 2430 by means of flexible coupler 2460. Both the aforementioned bearing 2456 a and bearing 2462 b, which also supports the proximal end of lead screw 2430, support coupler 2460. Bearing 2458 supports the distal end of lead screw 2430. Threaded lead screw 2430 is oriented so that it is effectively parallel with linear rail 2470. Lead screw 2430 also engages traveler 2480, which is described in more detail below, so that as lead screw 2430 is rotated, traveler 2420 moves along rail 2470. Turnbuckle 2415 couples traveler 2420 to tumble drive arm 2742 so that as traveler 2420 moves, side support 2740 b is rotated about the axis 2201 defined by stepped shafts 2510 b and 2510 a, causing an attached load to rotate about the tumble axis 2201, as described in the previous two embodiments. Turnbuckle 2415 includes ends 2416 a and 2416 b, which are threaded on to a central shaft. Thus by rotating the central shaft with the ends held fixed, one can adjust the length of turnbuckle 2415 as may be required for a specific situation. Additionally, traveler 2420 includes a number of alternative connection points 2421 where turnbuckle end 2416 a may be connected to provide relatively gross adjustments. Turnbuckle ends preferable include spherical bearings through which attachment screws 2417 and 2743 pass for fastening to traveler 2420 and tumble drive arm 2742 respectively; these provide necessary motion freedom in the angle of turnbuckle 2415 relative to arm 2290 as the load is rotated about the theta axis.

Referring to FIGS. 22 through 25A, the structure and function of traveler 2420 and its relationship to linear rail 2470 is now discussed in more detail. FIG. 22 is a perspective view of tumble assembly 2500, comprising the previously described handle 2280, shaft 2450, flexible coupler 2460, traveler 2420, linear rail 2470, lead screw 2430, bearings 2452 a, 2454, 2452 b, 2456 a, 2456 b, and 2458, and angle bar 2410.

Referring to FIG. 22A, which provides a magnification of the region included in circle A of FIG. 22, traveler 2420 includes traveler block 2424, end plates 2422 a and 2422 b (only end plate 2422 b is visible in the figure), threaded turnbuckle attachment holes 2421, and linear bearings 2425 a and 2425 b. Linear bearings 2425 a and 2425 b engage linear rail 2470, which is attached to cradle side 2290 b. Lead screw 2430 passes through traveler 2420. Traveler 2420 is held so that it does not contact angle bar 2410.

FIG. 23 provides a perspective view of traveler block 2424. It includes groove 2510 for receiving linear bearings 2425 a and 2425 b and screw clearance holes 2511. Cylindrical hole 2515 extends the full length of block 2424 and is open at both ends. At the bottom of hole 2512 is key groove 2518, which also extends the full length of block 2424. For each screw clearance hole 2511 there is a corresponding, coaxial, larger-diameter tooling hole 2512. Tooling holes allow screw clearance holes 2511 to be counter-bored within cylindrical opening 2515 and also allow linear-bearing securing screws to be inserted and with their screw heads nestled in the counter-bores.

FIG. 24 provides a perspective view of cylindrical nut 2520, which includes threaded through hole 2525 and key slot 2522. Cylindrical hole 2515 in block 2424 is sized to receive nut 2520 and to allow nut 2520 to slide with relatively low friction therein. Threaded through hole 2525 is threaded to receive lead screw 2430.

FIG. 25 is the same perspective view of tumble assembly 2500 as is provided in FIG. 22, except that traveler block 2424 is shown with portions cut away. The detailed view of FIG. 25A provides a magnified view inside traveler 2420. Referring to FIGS. 23-25A, key 2524 is inserted into slot 2522 of cylindrical nut 2520, and the combination is inserted into cylindrical hole 2515 of tumble block 2424, with key 2524 fitting into groove 2518. Thus, nut 2520 is prevented from rotating within block 2524, but it is free to slide linearly. Compression spring 2530 a is fitted between endplate 2422 a and nut 2520. Similarly, compression spring 2530 b is fitted between endplate 2422 b and nut 2520. With endplates 2422 a and 2422 b installed and secured with screws to block 2424, both springs 2530 a and 2530 b are compressed and provide a biasing assembly. Both end plates 2422 a and 2422 b include a hole 2423 a and 2423 b, respectively, located and sized to allow free passage of lead screw 2430. Thus, lead screw 2430 passes through endplate 2422 a and compression spring 2530 a, is threaded through nut 2520, and then passes through compression spring 2530 b and finally through endplate 2422 b.

Accordingly, rotation of tumble drive handle 2480 causes corresponding rotation of shaft 2450 and lead screw 2430. Nut 2520 is prevented from rotating in block 2424, and block 2424 is prevented from rotating due to its coupling to linear rail 2740 by means of linear bearings 2425 a and 2425 b. Thus, nut 2520 moves linearly along lead screw 2430. As nut 2520 is urged to move linearly, force is transferred to and exerted on traveler block 2424 via either of springs 2530 a and 2530 b and respective endplates 2422 a and 2422 b. Thus, rotation of drive handle 2480 causes traveler 2420 to travel linearly along lead screw 2430 with liner rail 2470 providing support, auxiliary guidance, and prevention of rotation. (Of course drive handle 2480 could readily be replaced by another type of actuator to provide automation and/or remote control.) As stated previously, the linear motion of traveler 2420 is coupled to side support 2740 b by means of turnbuckle 2417 and tumble drive arm 2742, thus causing the supported load to be rotated about the tumble axis 2201.

Compression springs 2530 a and 2530 b provide resilient compliance for tumble motion of the load. In particular, the threads incorporated in lead screw 2430 and nut 2520 are such that the mechanism is not back drivable. Thus, a force acting on the load in a manner to cause it to rotate about the tumble axis will cause it to rotate to an extent allowed by the further compression of one of springs 2530 a and 2530 b and the lengthening of the other. This is facilitated by the fact that nut 2520 and key 2524 may be easily moved linearly within block 2424. Thus, the load may be tumbled by an external force, which is compliance. Further, when the force is removed, springs 2530 a and 2530 b will exert forces that attempt to move the load back to its original position, which is resilience.

It is seen that if a theta adjustment is made in the present embodiment, either by means of rotating a theta drive handle 2270 a or 2270 b or by means of applying an external force, carriage plate 2750 b will move linearly. Because carriage plate 2750 b is attached to tumble mechanism 2500 by means of angle brace 2405 and is slidingly attached to cradle arm 2290 b by bearings 2452 a and 2452 b and linear bearings 2530 a and 2530 b, tumble mechanism 2500 will move linearly with carriage plate 2750 b, maintaining the relationship between traveler 2420 and tumble drive arm 2742. Thus, theta motion will not change or effect the orientation of the load with respect to the tumble axis 2201. As with the first two embodiments, tumble motion and theta motion are independent, compliant, resilient, and each is controllable by a single actuator.

In considering the foregoing alternative embodiments 200, 1200 and 2200, it is apparent that combinations of selected features or aspects taken from two or all three of the embodiments could be combined to form further embodiments of the invention. Similarly, various features may be utilized independent of one another or in conjunction with other manipulator systems. For example, the theta motion and compliance assemblies may be used independent of the tumble motion and compliance assemblies and vice versa.

Referring to FIGS. 26 through 29D, an alternative embodiment of the present invention will be described. In this embodiment of the invention, the system 100 is shown with tethers that are used to support “cables” or “cable assemblies” which are coupled to test head 110. As shown in FIG. 26, cables 2612, 2617, 2622 may extend from test cabinet 190 to test head 110. (Note, for simplicity reasons, cables were not included in the system drawings of FIGS. 1A and 1B, which were provided in regards to other aspects of the present invention.) When referring to “cables” or “cable assemblies,” this refers to any type of elongated member that is coupled to test head 110. This may include, for example, electrical cables, air conduits, water conduits, etc. For example, the “cables” in FIG. 26 include flexible air duct 2612, liquid coolant tubing 2612, and electrical wiring 2622. It is desirable that those cables be supported in some manner. It is also desirable that as test head 110 is moved through its motion envelope (as described herein and in the previously mentioned co-pending PCT patent application), the cable supports also move in a manner so as to maintain the cable in an orientation that minimizes its effect on the ability of the test head to be moved compliantly by external forces, for example while docking.

In FIG. 26, liquid coolant tubes 2617 are supported by tether 2615, air duct 2612 is supported by tether 2610, and electrical wiring cable 2622 is supported by tether 2620. Sling 2640 is provided to couple air duct 2612 to tether 2610. Tethers 2610, 2615, and 2620 extend from boom 1650, which is rotatably coupled to the top of column 130 by means of swivel coupling 2640. Thus, boom 1650 may pivot about a vertical axis extending through column 130. Accordingly, as test head 110 is moved through its motion envelope (see previously mentioned co-pending PCT patent application for a description of these motions), boom 1650 may rotate with it in order to maintain a near constant distance between the points of support for the cables and the test head.

However, rotation of boom 1650 is not sufficient for effective cable control. It is also desirable to provide vertical motion to the points of cable support. It has been found that the amount and direction of vertical cable support motion that is desirable is dependent upon many factors including the size and resiliency of the cable itself, the motions required in day-to-day operation, the positions of the peripherals to be docked to, and other site specific factors. In some instances it may be desirable for the cable support points to move in the same direction as the test head. In other instances it has been found that moving the cable support in the opposite direction as the test head is beneficial, as this tends to keep the cable straight. In either case there may be circumstances where it is desirable that the cable support points move the same distance as the test head. In other circumstances it may be desirable that the cable support points move a fraction of the distance that the test head moves. Although system 100 in FIG. 26 shows three cables and three supports, it may be desirable to bundle two or more cable entities into a single cable entity. For example, coolant tubes 2617 and air duct 2612 might be bundled together into a single entity. For a given class of test system, such bundling could be different from one user site to the next. Thus, a system, which provides the flexibility of having a variable number of supports is desirable. As will be described the present invention enables a manipulator system 100 to be adapted to such differing situational requirements.

In an exemplary embodiment of the present invention as illustrated in FIG. 26, tethers 2615, 2610, and 2620 are routed, through appropriate openings, up into boom 1650 where they encounter pulleys which direct them along boom 1650 towards swivel coupling 2640. They are then directed downwards into column 130 where they may be further routed terminated in various ways to produce different effects.

FIG. 27 provides a schematic illustration of a first exemplary embodiment. Three cables (not necessarily the same as those in FIG. 26) 2616, 2611, and 2621 are supported by tethers 2615, 2610, and 2620 respectively. Tethers 2615, 2610, and 2620 pass thorough respective openings 2619, 2614, and 2624 in the bottom of boom 1650 and then engage respective pulleys 2618, 2613, and 2623. Thus, tethers 2615, 2610, and 2620 are directed generally horizontally along boom 1650 towards column 130. Tethers 2615, 2610, and 2620 next engage pulleys 2631, 2632, and 2633 respectively, which direct tethers 2615, 2610, and 2620 downwards through opening 2641 in the bottom of boom 1650, through swivel coupling 2640, and then through opening 2642 in the top of column 130. Because, pulleys 2631, 2632, and 2633 are located approximately directly above swivel coupling 2640, boom 1650 may pivot approximately 90 degrees or more about swivel coupling 2640 without undue resistance from tethers 2615, 2610, and 2620 and without adversely effecting tethers 2615, 2610, and 2620.

The arrangement just described and depicted in FIG. 27 allows each of the tethers to be treated individually. Each tether may implement a different motion strategy. For example tether 2615 could move cable 2616 up while tether 2610 moves cable 2611 down. As another example, two tethers may be configured to move in the same direction but at different speeds. Also there are numerous materials that tethers may be made of including fibrous ropes, wire cables, flat-woven straps, etc. Each type of cable generally requires a particular style of pulley for best operation. Thus, if an application requires two tethers to be of different materials, it can be accommodated because each tether is assigned its own unique set of pulleys.

However, there may be situations where requirements can be satisfied by having all tethers behave in the same fashion. In such cases the boom apparatus may be simplified. FIG. 28 is provided to schematically illustrate another exemplary embodiment in which all tethers operate in the same fashion. FIG. 28 has one significant difference in comparison to FIG. 27. Because all three tethers 2615, 2610, and 2620 move in unison, they are all able to share common pulley 2630 to effect their turning from boom 1650 into column 130. Thus, the three pulleys 2631, 2632, and 2633 of FIG. 28 are replaced by a single pulley 2630. If tethers 2615, 2610, and 2620 are made of a material that is round in cross section, such as rope, pulley 2630 may be one of a style that allows tethers 2615, 2610, and 2620 to ride it side-by-side (perhaps each having its own groove to prevent harmful over rides). However, in a preferred version of this exemplary embodiment, tethers 2615, 2610, and 2620 are made a flat, woven strapping. In this case pulley 2630 may have a flat surface and tethers 2615, 2610, and 2620 may round pulley 2630 stacked one on top of another. If the diameter of pulley 2630 is relatively large in comparison to the thickness of the strapping, any slippage between adjacent straps will be minimal.

Although we have so far considered exemplary systems that include three tethers, it is clear any practical number of tethers may be accommodated, for example from just one to as many as four or five. Thus, a system may be designed and manufactured so that it can be adapted to handle any reasonable number of tethers according to application and situational needs that are not known a priori.

Referring to FIGS. 29A, 29B, 29C, and 29D, options in routing and terminating a tether within column 130 will be described. FIGS. 29A, 29B, 29C, and 29D provide schematic illustrations based on a manipulator described in the co-pending PCT patent application noted previously, however, the invention is not limited to such and the cable handling systems described herein may be used with various types of manipulators, including the pneumatic system described below or in counterbalanced systems, for example, as described in U.S. Pat. Nos. 4,527,942 and 6,396,257 and co-pending provisional patent application No. 61/037,065, which are incorporated herein by reference.

Thus, in FIGS. 29A, 29B, 29C, and 29D, test head 110 is coupled to arm unit 140, which may move vertically along the exterior of column 130. Pneumatic cylinder 4010 includes piston 4012, which is connected to piston rod 4014. Lift carriage 4020 includes pulleys 4025 and is supported by piston rod 4014. Supporting cable or strap 4030 is secured to a stationary point relative to column 130, led over pulleys 4025 and downwards to support arm unit 140 and test head 110. thus, vertical motion of piston 4012, effected by adding or releasing air from cylinder 4010 causes vertical motion of test head 110. Also, by maintaining a suitable air pressure within cylinder 4010, test head 110 may be kept in a substantially weightless or compliant condition with respect to vertical motion. Those familiar with the art will recognize that test head 110 will move at twice the speed of lift carriage 4020. In other words motion of test head 110 through a certain distance corresponds to motion of lift carriage 4020 through half that distance.

Also in all FIGS. 29A, 29B, 29C, and 29D, exemplary cable 3611 is supported by exemplary sling 3640, which is in turn supported by exemplary tether 3610. Exemplary tether 3610 extends upwards from sling 3640 into boom 1650; it then rounds pulleys 3613 and 3630 and descends into column 130. In FIG. 29A, tether 3610 terminates directly onto lift carriage 4020. Thus as lift carriage 4020 moves up, sling 3640 and cable 3611 move down and vice versa. Also, sling 3620 and cable 3611 move the same distance that lift carriage 4020 moves. Because lift carriage 4020 moves half the distance that test head 110 move, cable 3611 also moves half the distance that test head 110 moves. Thus, the configuration illustrated by FIG. 29A provides a tether that moves a cable half the distance that the test head moves but in the opposite direction.

FIG. 29B illustrates an exemplary embodiment in which tether 3610 is led below lift carriage 4020, passed 180 degrees around pulley 4050, and is finally terminated on lift carriage 4020. Sling 3640 and cable 3611 move in the same direction as lift carriage 4020 in FIG. 29B. This is because the direction of tether 3610 is reversed in comparison to FIG. 29A when it terminates at lift carriage 4020. As in FIG. 29A, sling 3640 and cable 3611 move half the distance that test head 110 moves. Thus, the configuration illustrated by FIG. 29B provides a tether that moves a cable half the distance that the test head moves and in the same direction.

In FIGS. 29C and 29D, tether attachment bracket 4140 has been added to arm unit 140. Attachment bracket 4140 extends inside column 130 so that tether 3610 may be attached to it. Thus, in FIG. 29C tether 3610 is attached directly to attachment bracket 4140 so that sling 3640 and cable 3611 will move the same distance as arm unit 140 and test head 110, but in the opposite direction. In FIG. 29D, the direction of tether 3610 is reversed before it is attached to attachment bracket 4140. Thus, in this case sling 3640 and cable 3611 will move the same distance and in the same direction as arm unit 140 and test head 110. Thus, the configuration illustrated by FIG. 29C provides a tether that moves a cable the same distance that the test head moves but in the opposite direction. Also, the configuration illustrated by FIG. 29D provides a tether that moves a cable the same distance that the test head moves and in the same direction.

The concepts illustrated in the exemplary embodiments of FIGS. 29A through 29D may, of course be applied to any reasonable number of tethers within one system. In systems having independent tethers as described in relation to FIG. 27, each individual tether may have a unique routing and termination within column 130 so that the characteristics of each tether may, accordingly, be different from one another. Further, the concept of multiple tethers and different possible tether behaviors is not restricted to manipulators of the type used in the exemplary embodiments. By incorporating various pulleys and mechanical advantage devices they may be readily adapted to other pneumatic-operated manipulators as well as counterbalanced and “hard-driven” manipulators. Further, the invention is not limited to the possibilities that were presented. By incorporating various mechanical advantage devices such a ball screws, stepped pulleys, multi-part tackles, etc., an endless variety of options is available in providing cable support motions in the same of opposite directions as the test head and at speeds or distances traveled the same, a multiple of, or a fraction of the test head's.

Referring to FIGS. 30 through 33E, a similar cable handling assembly is shown and described for a counterbalanced manipulator system. Referring to FIGS. 30-32, tethers 8610 and 8615 are provided with appropriate coupling gear 8611 and 8616, such as slings or elastic cords, to support electrical wiring cables and coolant tubing or ducts which are coupled to the test head. Tethers 8610 and 8615 extend from boom 7650, which is rotatably coupled to the top of column 130 by means of swivel coupling 8640. Thus, boom 7650 may pivot about a vertical axis extending through column 130. Accordingly, as the test head is moved through its motion envelope, boom 7650 may rotate with it in order to maintain a near constant distance between the points of support for the cables and the test head.

The present exemplary embodiment shown in FIGS. 30-32 provides two tethers 8610 and 8615 as supports. Tethers 8610 and 8615 are routed, through appropriate openings, up into boom 7650 where they encounter pulleys which direct them along boom 7650 towards swivel coupling 8640. Tethers 8610 and 8615 are then directed downwards into column 130 where they are routed and terminated to produce the desired motion effect.

FIG. 32 provides a schematic illustration of the above. Two cable entities 8611 and 8616 are supported by tethers 8610 and 8615, respectively. Tethers 8610 and 8615 pass through respective openings 8614 and 8619 in the bottom of boom 7650 and then engage respective pulleys 8613 and 8618. Thus, tethers 8610 and 8615 are directed generally horizontally along boom 7650 towards column 130. In the present exemplary embodiment, requirements can be satisfied by having both tethers behave in the same fashion. Thus, both tethers 8610 and 8615 move in unison; and both simultaneously engage single pulley 8630, which directs them downwards through swivel coupling 8640 into column 130. Because, pulley 8630 is located approximately directly above swivel coupling 8640, boom 7650 may pivot approximately 90 degrees or more about swivel coupling 8640 without undue resistance from tethers 8610 and 8615 and without adversely effecting tethers 8610 and 8615.

If tethers 8610 and 8615 are made of a material that is round in cross section, such as rope, pulley 8630 may be one of a style that allows tethers 8610 and 8615 to ride it side-by-side (perhaps each having its own groove to prevent harmful over rides). However, in a preferred version of this exemplary embodiment, tethers 8610 and 8615 are made of a flat, woven strapping. In this case pulley 8630 may have a flat surface and tethers 8610 and 8615 may round pulley 8630 stacked one on top of another. If the diameter of pulley 8630 is relatively large in comparison to the thickness of the strapping, any slippage between adjacent straps will be minimal.

While two tethers are described and illustrated herein, any number of tethers may be accommodated, for example from just one to as many as four or more. Thus, a system may be designed and manufactured so that it can be adapted to handle any reasonable number of tethers according to application and situational needs that are not known a priori. In FIG. 30, for example, a number of pulley mounting points 7652 are shown, which enable a variable number of pulleys and pulley locations, enabling the system to be adapted to different situations and changing needs.

In FIG. 31, which is a detailed rear view of column 130 with the rear door removed, it is seen that tethers 8610 and 8615 are directed downwards and are fastened to an eyebolt attached to the upper surface of counterweight assembly 1500. Thus, the test head load, the counterweights and the tethers will all move vertically as a single unit. The situation is illustrated schematically for a single tether, say tether 8610, in FIG. 33A.

In FIG. 33A, a load 110 is supported by vertical carriage 140 that may move vertically along column 130. As can be seen, as the load 110 moves upwards, the counterweights 1500 move downwards and vice versa. The illustrated cable entity is supported by tether 8610. Tether 8610 passes over pulleys 8623 and 8630 within boom 7650 and is finally attached to the counterweights 1500. Thus, for example, as the load 110 is moved up a distance X, the counterweights 1500 move down the same distance X, causing the cable entity to be raised the distance X. Accordingly, this arrangement causes the cable support to be moved in the same direction and the same distance as the test head as desired.

In the embodiment illustrated in FIG. 33B, the tether 8610 passes around further pulleys and is attached to the lower surface of the counterweights 1500. As such, this arrangement causes the cable support to be moved the same distance as the test head, but in the opposite direction.

In the embodiment illustrated in FIG. 33C, the tether 8610 passes around additional pulleys 8625 and 8625 between the boom 7650 and the upper surface of counterweights 1500. The two additional pulleys 8625 and 8627 provide a three fold mechanical advantage. As such, this arrangement causes the cable support to be moved in the same direction as the test head and three times the distance as the test head.

In the embodiment illustrated in FIG. 33D, the tether 8610 passes around an additional pulley 8629 between the boom 7650 and the cable entity. The tether 8610 is also connected to the lower surface of the counterweights 1500. As such, this arrangement causes the cable support to be moved half the distance as the test head and in the opposite direction.

In the embodiment illustrated in FIG. 33E, the tether 8610 passes around additional pulleys 8625 and 8625 between the boom 7650 and the upper surface of counterweights 1500 and about additional pulley 8629 between the boom 7650 and the cable entity. As such, this arrangement causes the cable support to be moved in the same direction as the test head and one and one-half times the distance as the test head. These arrangements are for illustrative purposes only. Various configurations of pulleys and tethers may be utilized to obtain a desired relationship between load movement and cable movement.

While exemplary embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention.

Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention. 

What is claimed:
 1. A cable support sustem comprising; a support column which includes a lift carriage which moves up and down; an arm adapted to support a test head, said arm moves with said lift carriage; and one or more tethers configured to support a cable, said one or more tethers coupled to the lift carriage and which moves when the lift carriage moves, wherein the one or more tethers move the supported cable in the same or opposite direction as the test head moves at a rate that is different than the rate of motion at which the test head moves up and down.
 2. A cable support system as in claim 1 wherein each tether depends from a boom pivotally supported on the support column at a swivel coupling.
 3. A cable support system as in claim 2 wherein each tether extends through the boom, over at least one boom pulley, through the swivel coupling and into the support column.
 4. A cable support system as in claim 3 wherein each tether is attached to a test head counter force within the support column.
 5. A cable support system as in claim 4 wherein the test head counter force is provided by a fluid cylinder.
 6. A cable support system as in claim 4 wherein the test head counter force is provided by a counterweight.
 7. A cable support system as in claim 3 wherein each tether extends over a separate boom pulley and each boom pulley is located approximately directly above the swivel coupling.
 8. A cable support system as in claim 3 wherein all of the tethers extend over a single boom pulley and the boom pulley is located approximately directly above the swivel coupling.
 9. A cable support system as in claim 8 wherein the boom pulley defines distinct paths for the tethers.
 10. A cable support system as in claim 8 wherein the boom pulley includes a single path for the tethers and the tethers overlap one another.
 11. A cable support system as in claim 4 wherein one or more secondary pulleys are positioned between the boom pulley and the test head counter force, the boom pulley and the supported cable, or a combination thereof to control the direction of travel and the constant. 